5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ekansh Gupta quic_ekangupt@quicinc.com
commit 6ca4ea1f88a06a04ed7b2c9c6bf9f00833b68214 upstream.
For registered buffers, fastrpc driver sends the buffer information to remote subsystem. There is a problem with current implementation where the page address is being sent with an offset leading to improper buffer address on DSP. This is leads to functional failures as DSP expects base address in page information and extracts offset information from remote arguments. Mask the offset and pass the base page address to DSP.
This issue is observed is a corner case when some buffer which is registered with fastrpc framework is passed with some offset by user and then the DSP implementation tried to read the data. As DSP expects base address and takes care of offsetting with remote arguments, passing an offsetted address will result in some unexpected data read in DSP.
All generic usecases usually pass the buffer as it is hence is problem is not usually observed. If someone tries to pass offsetted buffer and then tries to compare data at HLOS and DSP end, then the ambiguity will be observed.
Fixes: 80f3afd72bd4 ("misc: fastrpc: consider address offset before sending to DSP") Cc: stable@kernel.org Signed-off-by: Ekansh Gupta quic_ekangupt@quicinc.com Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org Link: https://lore.kernel.org/r/20250110134239.123603-3-srinivas.kandagatla@linaro... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/misc/fastrpc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -801,7 +801,7 @@ static int fastrpc_get_args(u32 kernel,
vma = find_vma(current->mm, ctx->args[i].ptr); if (vma) - pages[i].addr += ctx->args[i].ptr - + pages[i].addr += (ctx->args[i].ptr & PAGE_MASK) - vma->vm_start;
pg_start = (ctx->args[i].ptr & PAGE_MASK) >> PAGE_SHIFT;