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/fat-fix-uninitialized-field-in-nostale-filehandles.patch
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@xxxxxxx>
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@xxxxxxx
Reported-by: syzbot+3ce5dea5b1539ff36769@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: ea3983ace6b7 ("fat: restructure export_operations")
Signed-off-by: Jan Kara <jack@xxxxxxx>
Acked-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Cc: Amir Goldstein <amir73il@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxx are
fat-fix-uninitialized-field-in-nostale-filehandles.patch
