The patch titled Subject: lib: scatterlist: fix sg_split_phys to preserve original scatterlist offsets has been added to the -mm mm-nonmm-unstable branch. Its filename is lib-scatterlist-fix-sg_split_phys-to-preserve-original-scatterlist-offsets.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: T Pratham t-pratham@ti.com Subject: lib: scatterlist: fix sg_split_phys to preserve original scatterlist offsets Date: Wed, 19 Mar 2025 16:44:38 +0530

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 ---

lib/sg_split.c | 2 -- 1 file changed, 2 deletions(-)

--- a/lib/sg_split.c~lib-scatterlist-fix-sg_split_phys-to-preserve-original-scatterlist-offsets +++ a/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; _

Patches currently in -mm which might be from t-pratham@ti.com are

lib-scatterlist-fix-sg_split_phys-to-preserve-original-scatterlist-offsets.patch