The patch titled Subject: fat: Fix uninitialized field in nostale filehandles has been added to the -mm mm-nonmm-unstable branch. Its filename is fat-fix-uninitialized-field-in-nostale-filehandles.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: Jan Kara jack@suse.cz Subject: fat: Fix uninitialized field in nostale filehandles Date: Mon, 5 Feb 2024 13:26:26 +0100

When fat_encode_fh_nostale() encodes file handle without a parent it stores only first 10 bytes of the file handle. However the length of the file handle must be a multiple of 4 so the file handle is actually 12 bytes long and the last two bytes remain uninitialized. This is not great at we potentially leak uninitialized information with the handle to userspace. Properly initialize the full handle length.

Link: https://lkml.kernel.org/r/20240205122626.13701-1-jack@suse.cz Reported-by: syzbot+3ce5dea5b1539ff36769@syzkaller.appspotmail.com Fixes: ea3983ace6b7 ("fat: restructure export_operations") Signed-off-by: Jan Kara jack@suse.cz Acked-by: OGAWA Hirofumi hirofumi@mail.parknet.co.jp Cc: Amir Goldstein amir73il@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/fat/nfs.c | 6 ++++++ 1 file changed, 6 insertions(+)

--- a/fs/fat/nfs.c~fat-fix-uninitialized-field-in-nostale-filehandles +++ a/fs/fat/nfs.c @@ -130,6 +130,12 @@ fat_encode_fh_nostale(struct inode *inod fid->parent_i_gen = parent->i_generation; type = FILEID_FAT_WITH_PARENT; *lenp = FAT_FID_SIZE_WITH_PARENT; + } else { + /* + * We need to initialize this field because the fh is actually + * 12 bytes long + */ + fid->parent_i_pos_hi = 0; }

return type; _

Patches currently in -mm which might be from jack@suse.cz are

fat-fix-uninitialized-field-in-nostale-filehandles.patch