5.4-stable review patch. If anyone has any objections, please let me know.
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From: T Pratham t-pratham@ti.com
commit 8b46fdaea819a679da176b879e7b0674a1161a5e upstream.
The split_sg_phys function was incorrectly setting the offsets of all scatterlist entries (except the first) to 0. Only the first scatterlist entry's offset and length needs to be modified to account for the skip. Setting the rest entries' offsets to 0 could lead to incorrect data access.
I am using this function in a crypto driver that I'm currently developing (not yet sent to mailing list). During testing, it was observed that the output scatterlists (except the first one) contained incorrect garbage data.
I narrowed this issue down to the call of sg_split(). Upon debugging inside this function, I found that this resetting of offset is the cause of the problem, causing the subsequent scatterlists to point to incorrect memory locations in a page. By removing this code, I am obtaining expected data in all the split output scatterlists. Thus, this was indeed causing observable runtime effects!
This patch removes the offending code, ensuring that the page offsets in the input scatterlist are preserved in the output scatterlist.
Link: https://lkml.kernel.org/r/20250319111437.1969903-1-t-pratham@ti.com Fixes: f8bcbe62acd0 ("lib: scatterlist: add sg splitting function") Signed-off-by: T Pratham t-pratham@ti.com Cc: Robert Jarzmik robert.jarzmik@free.fr Cc: Jens Axboe axboe@kernel.dk Cc: Kamlesh Gurudasani kamlesh@ti.com Cc: Praneeth Bajjuri praneeth@ti.com Cc: Vignesh Raghavendra vigneshr@ti.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- lib/sg_split.c | 2 -- 1 file changed, 2 deletions(-)
--- a/lib/sg_split.c +++ b/lib/sg_split.c @@ -88,8 +88,6 @@ static void sg_split_phys(struct sg_spli if (!j) { out_sg->offset += split->skip_sg0; out_sg->length -= split->skip_sg0; - } else { - out_sg->offset = 0; } sg_dma_address(out_sg) = 0; sg_dma_len(out_sg) = 0;