This is a note to let you know that I've just added the patch titled
fat: fix uninitialized field in nostale filehandles
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fat-fix-uninitialized-field-in-nostale-filehandles.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b31b138105b9b15d2a4a8cee6f56fad8bd90540a
Author: Jan Kara <jack@xxxxxxx>
Date: Mon Feb 5 13:26:26 2024 +0100
fat: fix uninitialized field in nostale filehandles
[ Upstream commit fde2497d2bc3a063d8af88b258dbadc86bd7b57c ]
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>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/fat/nfs.c b/fs/fat/nfs.c
index af191371c3529..bab63eeaf9cbc 100644
--- a/fs/fat/nfs.c
+++ b/fs/fat/nfs.c
@@ -130,6 +130,12 @@ fat_encode_fh_nostale(struct inode *inode, __u32 *fh, int *lenp,
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;
