| Message ID | 20240822105933.2644945-4-quic_ekangupt@quicinc.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Add missing fixes to FastRPC driver | expand |
On Thu, Aug 22, 2024 at 04:29:33PM GMT, Ekansh Gupta wrote: > If multiple dma handles are passed with same fd over a remote call > the kernel driver takes a reference and expects that put for the > map will be called as many times to free the map. > But DSP only > updates the fd one time in the fd list when the DSP refcount > goes to zero I'm sorry, I couldn't understand this phrase. Could you plese clarify what do you mean here? > and hence kernel make put call only once for the > fd. This can cause SMMU fault issue as the same fd can be used > in future for some other call. > > Fixes: 35a82b87135d ("misc: fastrpc: Add dma handle implementation") > Cc: stable <stable@kernel.org> > Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> > --- > drivers/misc/fastrpc.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index ebe828770a8d..ad56e918e1f8 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -755,7 +755,7 @@ static const struct dma_buf_ops fastrpc_dma_buf_ops = { > > static int fastrpc_map_create(struct fastrpc_user *fl, int fd, > u64 va, u64 len, u32 attr, > - struct fastrpc_map **ppmap) > + struct fastrpc_map **ppmap, bool take_ref) > { > struct fastrpc_session_ctx *sess = fl->sctx; > struct fastrpc_map *map = NULL; > @@ -763,7 +763,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd, > struct scatterlist *sgl = NULL; > int err = 0, sgl_index = 0; > > - if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, true)) > + if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, take_ref)) > return 0; > > map = kzalloc(sizeof(*map), GFP_KERNEL); > @@ -917,14 +917,17 @@ static int fastrpc_create_maps(struct fastrpc_invoke_ctx *ctx) > int i, err; > > for (i = 0; i < ctx->nscalars; ++i) { > + bool take_ref = true; > > if (ctx->args[i].fd == 0 || ctx->args[i].fd == -1 || > ctx->args[i].length == 0) > continue; > > + if (i >= ctx->nbufs) > + take_ref = false; Please clarify too. > err = fastrpc_map_create(ctx->fl, ctx->args[i].fd, > (u64)ctx->args[i].ptr, ctx->args[i].length, > - ctx->args[i].attr, &ctx->maps[i]); > + ctx->args[i].attr, &ctx->maps[i], take_ref); > if (err) { > dev_err(dev, "Error Creating map %d\n", err); > return -EINVAL; > @@ -1417,7 +1420,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl, > > if (init.filelen && init.filefd) { > err = fastrpc_map_create(fl, init.filefd, init.file, > - init.filelen, 0, &map); > + init.filelen, 0, &map, true); > if (err) > goto err; > } > @@ -2040,7 +2043,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp) > > /* create SMMU mapping */ > err = fastrpc_map_create(fl, req.fd, req.vaddrin, req.length, > - 0, &map); > + 0, &map, true); > if (err) { > dev_err(dev, "failed to map buffer, fd = %d\n", req.fd); > return err; > -- > 2.34.1 >
On 8/30/2024 3:03 PM, Dmitry Baryshkov wrote: > On Thu, Aug 22, 2024 at 04:29:33PM GMT, Ekansh Gupta wrote: >> If multiple dma handles are passed with same fd over a remote call >> the kernel driver takes a reference and expects that put for the >> map will be called as many times to free the map. >> But DSP only >> updates the fd one time in the fd list when the DSP refcount >> goes to zero > I'm sorry, I couldn't understand this phrase. Could you plese clarify > what do you mean here? DMA handle are buffers passed to DSP which are only unmapped when DSP updated the buffer fd in fdlist. fdlist implementation: misc: fastrpc: Add fdlist implementation - kernel/git/next/linux-next.git - The linux-next integration testing tree <https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/misc/fastrpc.c?id=8f6c1d8c4f0cc316b0456788fff8373554d1d99d> A remote call payload carries both input/output buffers and dma handles. The lifetime of input/output buffer is a remote call which means that any buffer allocated or mapped for a remote call will be freed or unmapped when the remote call is completing. Whereas, dma handles can get freed over some other remote call whenever the DSP will update fdlist. So if a remote call passed multiple dma handles with same fd to DSP, on driver, ref count will be incremented, but DSP can update fdlist only 1 time for the same fd as DSP also has a ref counting happening for the dma handle and fdlist is updated when the DSP ref count goes to 0. In this case, the map will not get freed even though it is no longer in use. > >> and hence kernel make put call only once for the >> fd. This can cause SMMU fault issue as the same fd can be used >> in future for some other call. >> >> Fixes: 35a82b87135d ("misc: fastrpc: Add dma handle implementation") >> Cc: stable <stable@kernel.org> >> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> >> --- >> drivers/misc/fastrpc.c | 13 ++++++++----- >> 1 file changed, 8 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c >> index ebe828770a8d..ad56e918e1f8 100644 >> --- a/drivers/misc/fastrpc.c >> +++ b/drivers/misc/fastrpc.c >> @@ -755,7 +755,7 @@ static const struct dma_buf_ops fastrpc_dma_buf_ops = { >> >> static int fastrpc_map_create(struct fastrpc_user *fl, int fd, >> u64 va, u64 len, u32 attr, >> - struct fastrpc_map **ppmap) >> + struct fastrpc_map **ppmap, bool take_ref) >> { >> struct fastrpc_session_ctx *sess = fl->sctx; >> struct fastrpc_map *map = NULL; >> @@ -763,7 +763,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd, >> struct scatterlist *sgl = NULL; >> int err = 0, sgl_index = 0; >> >> - if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, true)) >> + if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, take_ref)) >> return 0; >> >> map = kzalloc(sizeof(*map), GFP_KERNEL); >> @@ -917,14 +917,17 @@ static int fastrpc_create_maps(struct fastrpc_invoke_ctx *ctx) >> int i, err; >> >> for (i = 0; i < ctx->nscalars; ++i) { >> + bool take_ref = true; >> >> if (ctx->args[i].fd == 0 || ctx->args[i].fd == -1 || >> ctx->args[i].length == 0) >> continue; >> >> + if (i >= ctx->nbufs) >> + take_ref = false; > Please clarify too. nbufs -> total input/output buffers nscalars -> nbufs + dma handles So here, avoiding ref increment for dma handles. > >> err = fastrpc_map_create(ctx->fl, ctx->args[i].fd, >> (u64)ctx->args[i].ptr, ctx->args[i].length, >> - ctx->args[i].attr, &ctx->maps[i]); >> + ctx->args[i].attr, &ctx->maps[i], take_ref); >> if (err) { >> dev_err(dev, "Error Creating map %d\n", err); >> return -EINVAL; >> @@ -1417,7 +1420,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl, >> >> if (init.filelen && init.filefd) { >> err = fastrpc_map_create(fl, init.filefd, init.file, >> - init.filelen, 0, &map); >> + init.filelen, 0, &map, true); >> if (err) >> goto err; >> } >> @@ -2040,7 +2043,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp) >> >> /* create SMMU mapping */ >> err = fastrpc_map_create(fl, req.fd, req.vaddrin, req.length, >> - 0, &map); >> + 0, &map, true); >> if (err) { >> dev_err(dev, "failed to map buffer, fd = %d\n", req.fd); >> return err; >> -- >> 2.34.1 >>
On Thu, Sep 19, 2024 at 12:00:33PM GMT, Ekansh Gupta wrote: > > > On 8/30/2024 3:03 PM, Dmitry Baryshkov wrote: > > On Thu, Aug 22, 2024 at 04:29:33PM GMT, Ekansh Gupta wrote: > >> If multiple dma handles are passed with same fd over a remote call > >> the kernel driver takes a reference and expects that put for the > >> map will be called as many times to free the map. > >> But DSP only > >> updates the fd one time in the fd list when the DSP refcount > >> goes to zero > > I'm sorry, I couldn't understand this phrase. Could you plese clarify > > what do you mean here? > DMA handle are buffers passed to DSP which are only unmapped when DSP updated > the buffer fd in fdlist. > fdlist implementation: misc: fastrpc: Add fdlist implementation - kernel/git/next/linux-next.git - The linux-next integration testing tree <https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/misc/fastrpc.c?id=8f6c1d8c4f0cc316b0456788fff8373554d1d99d> > > A remote call payload carries both input/output buffers and dma handles. The lifetime > of input/output buffer is a remote call which means that any buffer allocated or mapped > for a remote call will be freed or unmapped when the remote call is completing. Whereas, > dma handles can get freed over some other remote call whenever the DSP will update > fdlist. So if a remote call passed multiple dma handles with same fd to DSP, on driver, ref > count will be incremented, but DSP can update fdlist only 1 time for the same fd as DSP also > has a ref counting happening for the dma handle and fdlist is updated when the DSP ref > count goes to 0. In this case, the map will not get freed even though it is no longer in use. OK, I started looking at the related code. Pleas fix possible map leak in fastrpc_put_args(), happening if the copy_to_user() fails. Second. Please merge fastrpc_map_lookup() + fastrpc_map_put() invocation into a single call, effectively dropping take_ref argument from fastrpc_map_lookup() (which can now become fastrpc_map_get()). Now back to your patch. Please clarify if my understanding is correct: The driver maps dma bufs and passes them to DSP. Then once DSP firmware finds out that a particular buffer is no longer needed, it returns its fd via the fdlist part of the invoke_buf. As these buffers are returned only once, when they are no longer necessary, the kernel should not take additional references on the long-living dma-bufs. If that's the case, see my comments below. > > > >> and hence kernel make put call only once for the > >> fd. This can cause SMMU fault issue as the same fd can be used > >> in future for some other call. > >> > >> Fixes: 35a82b87135d ("misc: fastrpc: Add dma handle implementation") > >> Cc: stable <stable@kernel.org> > >> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> > >> --- > >> drivers/misc/fastrpc.c | 13 ++++++++----- > >> 1 file changed, 8 insertions(+), 5 deletions(-) > >> > >> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > >> index ebe828770a8d..ad56e918e1f8 100644 > >> --- a/drivers/misc/fastrpc.c > >> +++ b/drivers/misc/fastrpc.c > >> @@ -755,7 +755,7 @@ static const struct dma_buf_ops fastrpc_dma_buf_ops = { > >> > >> static int fastrpc_map_create(struct fastrpc_user *fl, int fd, > >> u64 va, u64 len, u32 attr, > >> - struct fastrpc_map **ppmap) > >> + struct fastrpc_map **ppmap, bool take_ref) > >> { > >> struct fastrpc_session_ctx *sess = fl->sctx; > >> struct fastrpc_map *map = NULL; > >> @@ -763,7 +763,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd, > >> struct scatterlist *sgl = NULL; > >> int err = 0, sgl_index = 0; > >> > >> - if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, true)) > >> + if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, take_ref)) > >> return 0; Do not add the take_ref argument to fastrpc_map_create(). Instead extract the rest of the code to the function fastrpc_map_attach() (or something like that). > >> > >> map = kzalloc(sizeof(*map), GFP_KERNEL); > >> @@ -917,14 +917,17 @@ static int fastrpc_create_maps(struct fastrpc_invoke_ctx *ctx) > >> int i, err; > >> > >> for (i = 0; i < ctx->nscalars; ++i) { > >> + bool take_ref = true; > >> > >> if (ctx->args[i].fd == 0 || ctx->args[i].fd == -1 || > >> ctx->args[i].length == 0) > >> continue; > >> > >> + if (i >= ctx->nbufs) > >> + take_ref = false; > > Please clarify too. > nbufs -> total input/output buffers > nscalars -> nbufs + dma handles > So here, avoiding ref increment for dma handles. > > > >> err = fastrpc_map_create(ctx->fl, ctx->args[i].fd, > >> (u64)ctx->args[i].ptr, ctx->args[i].length, > >> - ctx->args[i].attr, &ctx->maps[i]); > >> + ctx->args[i].attr, &ctx->maps[i], take_ref); Call conditionally either fastrpc_map_create() or fastrpc_map_attach(). > >> if (err) { > >> dev_err(dev, "Error Creating map %d\n", err); > >> return -EINVAL; > >> @@ -1417,7 +1420,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl, > >> > >> if (init.filelen && init.filefd) { > >> err = fastrpc_map_create(fl, init.filefd, init.file, > >> - init.filelen, 0, &map); > >> + init.filelen, 0, &map, true); > >> if (err) > >> goto err; > >> } > >> @@ -2040,7 +2043,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp) > >> > >> /* create SMMU mapping */ > >> err = fastrpc_map_create(fl, req.fd, req.vaddrin, req.length, > >> - 0, &map); > >> + 0, &map, true); > >> if (err) { > >> dev_err(dev, "failed to map buffer, fd = %d\n", req.fd); > >> return err; > >> -- > >> 2.34.1 > >> >
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index ebe828770a8d..ad56e918e1f8 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -755,7 +755,7 @@ static const struct dma_buf_ops fastrpc_dma_buf_ops = { static int fastrpc_map_create(struct fastrpc_user *fl, int fd, u64 va, u64 len, u32 attr, - struct fastrpc_map **ppmap) + struct fastrpc_map **ppmap, bool take_ref) { struct fastrpc_session_ctx *sess = fl->sctx; struct fastrpc_map *map = NULL; @@ -763,7 +763,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd, struct scatterlist *sgl = NULL; int err = 0, sgl_index = 0; - if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, true)) + if (!fastrpc_map_lookup(fl, fd, va, len, ppmap, take_ref)) return 0; map = kzalloc(sizeof(*map), GFP_KERNEL); @@ -917,14 +917,17 @@ static int fastrpc_create_maps(struct fastrpc_invoke_ctx *ctx) int i, err; for (i = 0; i < ctx->nscalars; ++i) { + bool take_ref = true; if (ctx->args[i].fd == 0 || ctx->args[i].fd == -1 || ctx->args[i].length == 0) continue; + if (i >= ctx->nbufs) + take_ref = false; err = fastrpc_map_create(ctx->fl, ctx->args[i].fd, (u64)ctx->args[i].ptr, ctx->args[i].length, - ctx->args[i].attr, &ctx->maps[i]); + ctx->args[i].attr, &ctx->maps[i], take_ref); if (err) { dev_err(dev, "Error Creating map %d\n", err); return -EINVAL; @@ -1417,7 +1420,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl, if (init.filelen && init.filefd) { err = fastrpc_map_create(fl, init.filefd, init.file, - init.filelen, 0, &map); + init.filelen, 0, &map, true); if (err) goto err; } @@ -2040,7 +2043,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp) /* create SMMU mapping */ err = fastrpc_map_create(fl, req.fd, req.vaddrin, req.length, - 0, &map); + 0, &map, true); if (err) { dev_err(dev, "failed to map buffer, fd = %d\n", req.fd); return err;
If multiple dma handles are passed with same fd over a remote call the kernel driver takes a reference and expects that put for the map will be called as many times to free the map. But DSP only updates the fd one time in the fd list when the DSP refcount goes to zero and hence kernel make put call only once for the fd. This can cause SMMU fault issue as the same fd can be used in future for some other call. Fixes: 35a82b87135d ("misc: fastrpc: Add dma handle implementation") Cc: stable <stable@kernel.org> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com> --- drivers/misc/fastrpc.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)