| Message ID | 1690182571-7348-1-git-send-email-quic_ekangupt@quicinc.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] misc: fastrpc: Fix incorrect DMA mapping unmap request | expand |
On Mon, Jul 24, 2023 at 12:39:31PM +0530, Ekansh Gupta wrote: > Scatterlist table is obtained during map create request and the same I'm guessing that this all happens in fastrpc_map_create() where: map->table = dma_buf_map_attachment_unlocked(map->attach, DMA_BIDIRECTIONAL); fails, we jump to map_err, and then call fastrpc_map_put(map), which then ends up in the code below? > table is used for DMA mapping unmap. In case there is any failure > while getting the sg_table, ERR_PTR is returned instead of sg_table. The problem isn't that ERR_PTR() is being returned, the problem is that this is being assigned to map->table and you keep running. > > When the map is getting freed, there is only a non-NULL check of > sg_table which will also be true in case failure was returned instead > of sg_table. This would result in improper unmap request. Add proper > check to avoid bad unmap request. > > Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method") > Cc: stable <stable@kernel.org> > Tested-by: Ekansh Gupta <quic_ekangupt@quicinc.com> You always test your own patches, so no need to declare this. > Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> > --- > Changes in v2: > - Added fixes information to commit text > > drivers/misc/fastrpc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index 9666d28..75da69a 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -313,7 +313,7 @@ static void fastrpc_free_map(struct kref *ref) > > map = container_of(ref, struct fastrpc_map, refcount); > > - if (map->table) { > + if (map->table && !IS_ERR(map->table)) { Rather than carrying around an IS_ERR(map->table), I think you should address this at the originating place. E.g. assign the return value of the dma_buf_map_attachment_unlocked() to a local variable and only if it is valid you assign map->table. Or perhaps make it NULL in the error path. Regards, Bjorn > if (map->attr & FASTRPC_ATTR_SECUREMAP) { > struct qcom_scm_vmperm perm; > int vmid = map->fl->cctx->vmperms[0].vmid; > -- > 2.7.4 >
On 7/26/2023 12:00 PM, Bjorn Andersson wrote: > On Mon, Jul 24, 2023 at 12:39:31PM +0530, Ekansh Gupta wrote: >> Scatterlist table is obtained during map create request and the same > > I'm guessing that this all happens in fastrpc_map_create() where: > > map->table = dma_buf_map_attachment_unlocked(map->attach, DMA_BIDIRECTIONAL); > > fails, we jump to map_err, and then call fastrpc_map_put(map), which > then ends up in the code below? > yes, your understanding is correct. >> table is used for DMA mapping unmap. In case there is any failure >> while getting the sg_table, ERR_PTR is returned instead of sg_table. > > The problem isn't that ERR_PTR() is being returned, the problem is that > this is being assigned to map->table and you keep running. > >> >> When the map is getting freed, there is only a non-NULL check of >> sg_table which will also be true in case failure was returned instead >> of sg_table. This would result in improper unmap request. Add proper >> check to avoid bad unmap request. >> >> Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method") >> Cc: stable <stable@kernel.org> >> Tested-by: Ekansh Gupta <quic_ekangupt@quicinc.com> > > You always test your own patches, so no need to declare this. > sure, I'll avoid adding this for future changes. >> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> >> --- >> Changes in v2: >> - Added fixes information to commit text >> >> drivers/misc/fastrpc.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c >> index 9666d28..75da69a 100644 >> --- a/drivers/misc/fastrpc.c >> +++ b/drivers/misc/fastrpc.c >> @@ -313,7 +313,7 @@ static void fastrpc_free_map(struct kref *ref) >> >> map = container_of(ref, struct fastrpc_map, refcount); >> >> - if (map->table) { >> + if (map->table && !IS_ERR(map->table)) { > > Rather than carrying around an IS_ERR(map->table), I think you should > address this at the originating place. E.g. assign the return value of > the dma_buf_map_attachment_unlocked() to a local variable and only if it > is valid you assign map->table. Or perhaps make it NULL in the error > path. > understood, this looks much cleaner solution. I'll update this in the next patch. Thanks for taking your time to review this change, Bjorn. --ekansh > Regards, > Bjorn > >> if (map->attr & FASTRPC_ATTR_SECUREMAP) { >> struct qcom_scm_vmperm perm; >> int vmid = map->fl->cctx->vmperms[0].vmid; >> -- >> 2.7.4 >>
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 9666d28..75da69a 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -313,7 +313,7 @@ static void fastrpc_free_map(struct kref *ref) map = container_of(ref, struct fastrpc_map, refcount); - if (map->table) { + if (map->table && !IS_ERR(map->table)) { if (map->attr & FASTRPC_ATTR_SECUREMAP) { struct qcom_scm_vmperm perm; int vmid = map->fl->cctx->vmperms[0].vmid;
Scatterlist table is obtained during map create request and the same table is used for DMA mapping unmap. In case there is any failure while getting the sg_table, ERR_PTR is returned instead of sg_table. When the map is getting freed, there is only a non-NULL check of sg_table which will also be true in case failure was returned instead of sg_table. This would result in improper unmap request. Add proper check to avoid bad unmap request. Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method") Cc: stable <stable@kernel.org> Tested-by: Ekansh Gupta <quic_ekangupt@quicinc.com> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> --- Changes in v2: - Added fixes information to commit text drivers/misc/fastrpc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)