| Message ID | 20221128134832.84867-4-philmd@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | hw/display/qxl: Avoid buffer overrun in qxl_phys2virt() | expand |
Hi On Mon, Nov 28, 2022 at 5:48 PM Philippe Mathieu-Daudé <philmd@linaro.org> wrote: > Currently qxl_phys2virt() doesn't check for buffer overrun. > In order to do so in the next commit, pass the buffer size > as argument. > > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> > --- > RFC: Please double-check qxl_render_update_area_unlocked() > --- > hw/display/qxl-logger.c | 11 ++++++++--- > hw/display/qxl-render.c | 12 ++++++++---- > hw/display/qxl.c | 14 +++++++++----- > hw/display/qxl.h | 4 +++- > 4 files changed, 28 insertions(+), 13 deletions(-) > > diff --git a/hw/display/qxl-logger.c b/hw/display/qxl-logger.c > index 1bcf803db6..35c38f6252 100644 > --- a/hw/display/qxl-logger.c > +++ b/hw/display/qxl-logger.c > @@ -106,7 +106,7 @@ static int qxl_log_image(PCIQXLDevice *qxl, > QXLPHYSICAL addr, int group_id) > QXLImage *image; > QXLImageDescriptor *desc; > > - image = qxl_phys2virt(qxl, addr, group_id); > + image = qxl_phys2virt(qxl, addr, group_id, sizeof(QXLImage)); > if (!image) { > return 1; > } > @@ -214,7 +214,8 @@ int qxl_log_cmd_cursor(PCIQXLDevice *qxl, QXLCursorCmd > *cmd, int group_id) > cmd->u.set.position.y, > cmd->u.set.visible ? "yes" : "no", > cmd->u.set.shape); > - cursor = qxl_phys2virt(qxl, cmd->u.set.shape, group_id); > + cursor = qxl_phys2virt(qxl, cmd->u.set.shape, group_id, > + sizeof(QXLCursor)); > if (!cursor) { > return 1; > } > @@ -236,6 +237,7 @@ int qxl_log_command(PCIQXLDevice *qxl, const char > *ring, QXLCommandExt *ext) > { > bool compat = ext->flags & QXL_COMMAND_FLAG_COMPAT; > void *data; > + size_t datasz; > int ret; > > if (!qxl->cmdlog) { > @@ -249,15 +251,18 @@ int qxl_log_command(PCIQXLDevice *qxl, const char > *ring, QXLCommandExt *ext) > > switch (ext->cmd.type) { > case QXL_CMD_DRAW: > + datasz = compat ? sizeof(QXLCompatDrawable) : sizeof(QXLDrawable); > break; > case QXL_CMD_SURFACE: > + datasz = sizeof(QXLSurfaceCmd); > break; > case QXL_CMD_CURSOR: > + datasz = sizeof(QXLCursorCmd); > break; > default: > goto out; > } > - data = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id); > + data = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id, datasz); > if (!data) { > return 1; > } > diff --git a/hw/display/qxl-render.c b/hw/display/qxl-render.c > index ca217004bf..0a4bfa8aa6 100644 > --- a/hw/display/qxl-render.c > +++ b/hw/display/qxl-render.c > @@ -107,7 +107,9 @@ static void > qxl_render_update_area_unlocked(PCIQXLDevice *qxl) > qxl->guest_primary.resized = 0; > qxl->guest_primary.data = qxl_phys2virt(qxl, > > qxl->guest_primary.surface.mem, > - MEMSLOT_GROUP_GUEST); > + MEMSLOT_GROUP_GUEST, > + > qxl->guest_primary.abs_stride > + * height); > Right, it looks like QXL device stride is in bytes. Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> > if (!qxl->guest_primary.data) { > goto end; > } > @@ -228,7 +230,7 @@ static void qxl_unpack_chunks(void *dest, size_t size, > PCIQXLDevice *qxl, > if (offset == size) { > return; > } > - chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id); > + chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id, bytes); > if (!chunk) { > return; > } > @@ -295,7 +297,8 @@ fail: > /* called from spice server thread context only */ > int qxl_render_cursor(PCIQXLDevice *qxl, QXLCommandExt *ext) > { > - QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id); > + QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id, > + sizeof(QXLCursorCmd)); > QXLCursor *cursor; > QEMUCursor *c; > > @@ -314,7 +317,8 @@ int qxl_render_cursor(PCIQXLDevice *qxl, QXLCommandExt > *ext) > } > switch (cmd->type) { > case QXL_CURSOR_SET: > - cursor = qxl_phys2virt(qxl, cmd->u.set.shape, ext->group_id); > + cursor = qxl_phys2virt(qxl, cmd->u.set.shape, ext->group_id, > + sizeof(QXLCursor)); > if (!cursor) { > return 1; > } > diff --git a/hw/display/qxl.c b/hw/display/qxl.c > index 5b10f697f1..231d733250 100644 > --- a/hw/display/qxl.c > +++ b/hw/display/qxl.c > @@ -274,7 +274,8 @@ static void > qxl_spice_monitors_config_async(PCIQXLDevice *qxl, int replay) > QXL_IO_MONITORS_CONFIG_ASYNC)); > } > > - cfg = qxl_phys2virt(qxl, qxl->guest_monitors_config, > MEMSLOT_GROUP_GUEST); > + cfg = qxl_phys2virt(qxl, qxl->guest_monitors_config, > MEMSLOT_GROUP_GUEST, > + sizeof(QXLMonitorsConfig)); > if (cfg != NULL && cfg->count == 1) { > qxl->guest_primary.resized = 1; > qxl->guest_head0_width = cfg->heads[0].width; > @@ -459,7 +460,8 @@ static int qxl_track_command(PCIQXLDevice *qxl, struct > QXLCommandExt *ext) > switch (le32_to_cpu(ext->cmd.type)) { > case QXL_CMD_SURFACE: > { > - QXLSurfaceCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, > ext->group_id); > + QXLSurfaceCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, > ext->group_id, > + sizeof(QXLSurfaceCmd)); > > if (!cmd) { > return 1; > @@ -494,7 +496,8 @@ static int qxl_track_command(PCIQXLDevice *qxl, struct > QXLCommandExt *ext) > } > case QXL_CMD_CURSOR: > { > - QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, > ext->group_id); > + QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, > ext->group_id, > + sizeof(QXLCursorCmd)); > > if (!cmd) { > return 1; > @@ -1456,7 +1459,8 @@ static bool qxl_get_check_slot_offset(PCIQXLDevice > *qxl, QXLPHYSICAL pqxl, > } > > /* can be also called from spice server thread context */ > -void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, int group_id) > +void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, int group_id, > + size_t size) > { > uint64_t offset; > uint32_t slot; > @@ -1964,7 +1968,7 @@ static void qxl_dirty_surfaces(PCIQXLDevice *qxl) > } > > cmd = qxl_phys2virt(qxl, qxl->guest_surfaces.cmds[i], > - MEMSLOT_GROUP_GUEST); > + MEMSLOT_GROUP_GUEST, sizeof(QXLSurfaceCmd)); > assert(cmd); > assert(cmd->type == QXL_SURFACE_CMD_CREATE); > qxl_dirty_one_surface(qxl, cmd->u.surface_create.data, > diff --git a/hw/display/qxl.h b/hw/display/qxl.h > index 78b3a6c9ba..bf03138ab4 100644 > --- a/hw/display/qxl.h > +++ b/hw/display/qxl.h > @@ -153,6 +153,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(PCIQXLDevice, PCI_QXL) > * @qxl: QXL device > * @phys: physical offset of buffer within the VRAM > * @group_id: memory slot group > + * @size: size of the buffer > * > * Returns a host pointer to a buffer placed at offset @phys within the > * active slot @group_id of the PCI VGA RAM memory region associated with > @@ -166,7 +167,8 @@ OBJECT_DECLARE_SIMPLE_TYPE(PCIQXLDevice, PCI_QXL) > * the incoming ram_addr_t. > * > */ > -void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL phys, int group_id); > +void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL phys, int group_id, > + size_t size); > void qxl_set_guest_bug(PCIQXLDevice *qxl, const char *msg, ...) > G_GNUC_PRINTF(2, 3); > > -- > 2.38.1 > >
> @@ -228,7 +230,7 @@ static void qxl_unpack_chunks(void *dest, size_t size, PCIQXLDevice *qxl, > if (offset == size) { > return; > } > - chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id); > + chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id, bytes); > if (!chunk) { > return; > } Naa, its not that simple. You get a QXLDataChunk passed in which typically is verified *excluding* dynamically-sized chunk->data. Also at least one code path (processing SPICE_CURSOR_TYPE_MONO in qxl_cursor) goes access chunk.data[] without calling qxl_unpack_chunks(), that needs additional verification too (or switch it to call qxl_unpack_chunks, or just drop it because nobody uses mono chrome cursors anyway). take care, Gerd
On 28/11/22 16:08, Gerd Hoffmann wrote: >> @@ -228,7 +230,7 @@ static void qxl_unpack_chunks(void *dest, size_t size, PCIQXLDevice *qxl, >> if (offset == size) { >> return; >> } >> - chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id); >> + chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id, bytes); >> if (!chunk) { >> return; >> } > > Naa, its not that simple. You get a QXLDataChunk passed in which > typically is verified *excluding* dynamically-sized chunk->data. OK so IIUC 1/ this line should be: chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id, sizeof(QXLDataChunk)); but 2/ we should check chunk->data[chunk->data_size] is valid (within the MR) before calling the memcpy(), right? > Also at least one code path (processing SPICE_CURSOR_TYPE_MONO in > qxl_cursor) goes access chunk.data[] without calling > qxl_unpack_chunks(), that needs additional verification too (or > switch it to call qxl_unpack_chunks, or just drop it because nobody > uses mono chrome cursors anyway). OK I'll look at that. Thanks, Phil.
On Mon, Nov 28, 2022 at 04:41:14PM +0100, Philippe Mathieu-Daudé wrote: > On 28/11/22 16:08, Gerd Hoffmann wrote: > > > @@ -228,7 +230,7 @@ static void qxl_unpack_chunks(void *dest, size_t size, PCIQXLDevice *qxl, > > > if (offset == size) { > > > return; > > > } > > > - chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id); > > > + chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id, bytes); > > > if (!chunk) { > > > return; > > > } > > > > Naa, its not that simple. You get a QXLDataChunk passed in which > > typically is verified *excluding* dynamically-sized chunk->data. > > OK so IIUC 1/ this line should be: > > chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id, > sizeof(QXLDataChunk)); Depends on whenever you do (2) inside or outside the loop ;) > but 2/ we should check chunk->data[chunk->data_size] is valid (within > the MR) before calling the memcpy(), right? Yes. take care, Gerd
On 28/11/22 16:41, Philippe Mathieu-Daudé wrote: > On 28/11/22 16:08, Gerd Hoffmann wrote: >> Also at least one code path (processing SPICE_CURSOR_TYPE_MONO in >> qxl_cursor) goes access chunk.data[] without calling >> qxl_unpack_chunks(), that needs additional verification too (or >> switch it to call qxl_unpack_chunks, or just drop it because nobody >> uses mono chrome cursors anyway). Per commit 36ffc122dc ("qxl: support mono cursors with inverted colors") "Monochrome cursors are still used by Windows guests" (i.e. Win2008R2) :/
On 28/11/22 17:18, Philippe Mathieu-Daudé wrote: > On 28/11/22 16:41, Philippe Mathieu-Daudé wrote: >> On 28/11/22 16:08, Gerd Hoffmann wrote: > >>> Also at least one code path (processing SPICE_CURSOR_TYPE_MONO in >>> qxl_cursor) goes access chunk.data[] without calling >>> qxl_unpack_chunks(), that needs additional verification too (or >>> switch it to call qxl_unpack_chunks, or just drop it because nobody >>> uses mono chrome cursors anyway). > Per commit 36ffc122dc ("qxl: support mono cursors with inverted colors") > "Monochrome cursors are still used by Windows guests" (i.e. Win2008R2) > :/ Hmm I guess I'm missing something in qxl_cursor() following the SPICE_CURSOR_TYPE_MONO case. - cursor_alloc() allocate QEMUCursor* c but doesn't set c->data, - nothing seems to set c->data - cursor_set_mono() is called and *(c->data) is assigned... ?
On 28/11/22 17:29, Philippe Mathieu-Daudé wrote: > On 28/11/22 17:18, Philippe Mathieu-Daudé wrote: >> On 28/11/22 16:41, Philippe Mathieu-Daudé wrote: >>> On 28/11/22 16:08, Gerd Hoffmann wrote: >> >>>> Also at least one code path (processing SPICE_CURSOR_TYPE_MONO in >>>> qxl_cursor) goes access chunk.data[] without calling >>>> qxl_unpack_chunks(), that needs additional verification too (or >>>> switch it to call qxl_unpack_chunks, or just drop it because nobody >>>> uses mono chrome cursors anyway). >> Per commit 36ffc122dc ("qxl: support mono cursors with inverted colors") >> "Monochrome cursors are still used by Windows guests" (i.e. Win2008R2) >> :/ > > Hmm I guess I'm missing something in qxl_cursor() following the > SPICE_CURSOR_TYPE_MONO case. > > - cursor_alloc() allocate QEMUCursor* c but doesn't set c->data, Sorry long day, cursor_alloc() does allocate c->data: typedef struct QEMUCursor { int width, height; int hot_x, hot_y; int refcount; uint32_t data[]; } QEMUCursor; QEMUCursor *cursor_alloc(int width, int height) { QEMUCursor *c; size_t datasize = width * height * sizeof(uint32_t); if (width > 512 || height > 512) { return NULL; } c = g_malloc0(sizeof(QEMUCursor) + datasize); > - nothing seems to set c->data > - cursor_set_mono() is called and *(c->data) is assigned... > > ? >
diff --git a/hw/display/qxl-logger.c b/hw/display/qxl-logger.c index 1bcf803db6..35c38f6252 100644 --- a/hw/display/qxl-logger.c +++ b/hw/display/qxl-logger.c @@ -106,7 +106,7 @@ static int qxl_log_image(PCIQXLDevice *qxl, QXLPHYSICAL addr, int group_id) QXLImage *image; QXLImageDescriptor *desc; - image = qxl_phys2virt(qxl, addr, group_id); + image = qxl_phys2virt(qxl, addr, group_id, sizeof(QXLImage)); if (!image) { return 1; } @@ -214,7 +214,8 @@ int qxl_log_cmd_cursor(PCIQXLDevice *qxl, QXLCursorCmd *cmd, int group_id) cmd->u.set.position.y, cmd->u.set.visible ? "yes" : "no", cmd->u.set.shape); - cursor = qxl_phys2virt(qxl, cmd->u.set.shape, group_id); + cursor = qxl_phys2virt(qxl, cmd->u.set.shape, group_id, + sizeof(QXLCursor)); if (!cursor) { return 1; } @@ -236,6 +237,7 @@ int qxl_log_command(PCIQXLDevice *qxl, const char *ring, QXLCommandExt *ext) { bool compat = ext->flags & QXL_COMMAND_FLAG_COMPAT; void *data; + size_t datasz; int ret; if (!qxl->cmdlog) { @@ -249,15 +251,18 @@ int qxl_log_command(PCIQXLDevice *qxl, const char *ring, QXLCommandExt *ext) switch (ext->cmd.type) { case QXL_CMD_DRAW: + datasz = compat ? sizeof(QXLCompatDrawable) : sizeof(QXLDrawable); break; case QXL_CMD_SURFACE: + datasz = sizeof(QXLSurfaceCmd); break; case QXL_CMD_CURSOR: + datasz = sizeof(QXLCursorCmd); break; default: goto out; } - data = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id); + data = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id, datasz); if (!data) { return 1; } diff --git a/hw/display/qxl-render.c b/hw/display/qxl-render.c index ca217004bf..0a4bfa8aa6 100644 --- a/hw/display/qxl-render.c +++ b/hw/display/qxl-render.c @@ -107,7 +107,9 @@ static void qxl_render_update_area_unlocked(PCIQXLDevice *qxl) qxl->guest_primary.resized = 0; qxl->guest_primary.data = qxl_phys2virt(qxl, qxl->guest_primary.surface.mem, - MEMSLOT_GROUP_GUEST); + MEMSLOT_GROUP_GUEST, + qxl->guest_primary.abs_stride + * height); if (!qxl->guest_primary.data) { goto end; } @@ -228,7 +230,7 @@ static void qxl_unpack_chunks(void *dest, size_t size, PCIQXLDevice *qxl, if (offset == size) { return; } - chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id); + chunk = qxl_phys2virt(qxl, chunk->next_chunk, group_id, bytes); if (!chunk) { return; } @@ -295,7 +297,8 @@ fail: /* called from spice server thread context only */ int qxl_render_cursor(PCIQXLDevice *qxl, QXLCommandExt *ext) { - QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id); + QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id, + sizeof(QXLCursorCmd)); QXLCursor *cursor; QEMUCursor *c; @@ -314,7 +317,8 @@ int qxl_render_cursor(PCIQXLDevice *qxl, QXLCommandExt *ext) } switch (cmd->type) { case QXL_CURSOR_SET: - cursor = qxl_phys2virt(qxl, cmd->u.set.shape, ext->group_id); + cursor = qxl_phys2virt(qxl, cmd->u.set.shape, ext->group_id, + sizeof(QXLCursor)); if (!cursor) { return 1; } diff --git a/hw/display/qxl.c b/hw/display/qxl.c index 5b10f697f1..231d733250 100644 --- a/hw/display/qxl.c +++ b/hw/display/qxl.c @@ -274,7 +274,8 @@ static void qxl_spice_monitors_config_async(PCIQXLDevice *qxl, int replay) QXL_IO_MONITORS_CONFIG_ASYNC)); } - cfg = qxl_phys2virt(qxl, qxl->guest_monitors_config, MEMSLOT_GROUP_GUEST); + cfg = qxl_phys2virt(qxl, qxl->guest_monitors_config, MEMSLOT_GROUP_GUEST, + sizeof(QXLMonitorsConfig)); if (cfg != NULL && cfg->count == 1) { qxl->guest_primary.resized = 1; qxl->guest_head0_width = cfg->heads[0].width; @@ -459,7 +460,8 @@ static int qxl_track_command(PCIQXLDevice *qxl, struct QXLCommandExt *ext) switch (le32_to_cpu(ext->cmd.type)) { case QXL_CMD_SURFACE: { - QXLSurfaceCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id); + QXLSurfaceCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id, + sizeof(QXLSurfaceCmd)); if (!cmd) { return 1; @@ -494,7 +496,8 @@ static int qxl_track_command(PCIQXLDevice *qxl, struct QXLCommandExt *ext) } case QXL_CMD_CURSOR: { - QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id); + QXLCursorCmd *cmd = qxl_phys2virt(qxl, ext->cmd.data, ext->group_id, + sizeof(QXLCursorCmd)); if (!cmd) { return 1; @@ -1456,7 +1459,8 @@ static bool qxl_get_check_slot_offset(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, } /* can be also called from spice server thread context */ -void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, int group_id) +void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL pqxl, int group_id, + size_t size) { uint64_t offset; uint32_t slot; @@ -1964,7 +1968,7 @@ static void qxl_dirty_surfaces(PCIQXLDevice *qxl) } cmd = qxl_phys2virt(qxl, qxl->guest_surfaces.cmds[i], - MEMSLOT_GROUP_GUEST); + MEMSLOT_GROUP_GUEST, sizeof(QXLSurfaceCmd)); assert(cmd); assert(cmd->type == QXL_SURFACE_CMD_CREATE); qxl_dirty_one_surface(qxl, cmd->u.surface_create.data, diff --git a/hw/display/qxl.h b/hw/display/qxl.h index 78b3a6c9ba..bf03138ab4 100644 --- a/hw/display/qxl.h +++ b/hw/display/qxl.h @@ -153,6 +153,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(PCIQXLDevice, PCI_QXL) * @qxl: QXL device * @phys: physical offset of buffer within the VRAM * @group_id: memory slot group + * @size: size of the buffer * * Returns a host pointer to a buffer placed at offset @phys within the * active slot @group_id of the PCI VGA RAM memory region associated with @@ -166,7 +167,8 @@ OBJECT_DECLARE_SIMPLE_TYPE(PCIQXLDevice, PCI_QXL) * the incoming ram_addr_t. * */ -void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL phys, int group_id); +void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL phys, int group_id, + size_t size); void qxl_set_guest_bug(PCIQXLDevice *qxl, const char *msg, ...) G_GNUC_PRINTF(2, 3);
Currently qxl_phys2virt() doesn't check for buffer overrun. In order to do so in the next commit, pass the buffer size as argument. Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> --- RFC: Please double-check qxl_render_update_area_unlocked() --- hw/display/qxl-logger.c | 11 ++++++++--- hw/display/qxl-render.c | 12 ++++++++---- hw/display/qxl.c | 14 +++++++++----- hw/display/qxl.h | 4 +++- 4 files changed, 28 insertions(+), 13 deletions(-)