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| author | Anderson Nascimento <anderson@allelesecurity.com> | 2025-09-08 09:49:02 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-19 16:21:44 +0200 |
| commit | d3a9a8e1275eb9b87f006b5562a287aea3f6885f (patch) | |
| tree | ab47f9ab681724f0d4cfb522d9be2bc67bf3d0cf /fs | |
| parent | 184b0aab791a5c762edd90c89825e692422be82e (diff) | |
| download | linux-d3a9a8e1275eb9b87f006b5562a287aea3f6885f.tar.gz linux-d3a9a8e1275eb9b87f006b5562a287aea3f6885f.tar.bz2 linux-d3a9a8e1275eb9b87f006b5562a287aea3f6885f.zip | |
btrfs: avoid potential out-of-bounds in btrfs_encode_fh()
commit dff4f9ff5d7f289e4545cc936362e01ed3252742 upstream.
The function btrfs_encode_fh() does not properly account for the three
cases it handles.
Before writing to the file handle (fh), the function only returns to the
user BTRFS_FID_SIZE_NON_CONNECTABLE (5 dwords, 20 bytes) or
BTRFS_FID_SIZE_CONNECTABLE (8 dwords, 32 bytes).
However, when a parent exists and the root ID of the parent and the
inode are different, the function writes BTRFS_FID_SIZE_CONNECTABLE_ROOT
(10 dwords, 40 bytes).
If *max_len is not large enough, this write goes out of bounds because
BTRFS_FID_SIZE_CONNECTABLE_ROOT is greater than
BTRFS_FID_SIZE_CONNECTABLE originally returned.
This results in an 8-byte out-of-bounds write at
fid->parent_root_objectid = parent_root_id.
A previous attempt to fix this issue was made but was lost.
https://lore.kernel.org/all/4CADAEEC020000780001B32C@vpn.id2.novell.com/
Although this issue does not seem to be easily triggerable, it is a
potential memory corruption bug that should be fixed. This patch
resolves the issue by ensuring the function returns the appropriate size
for all three cases and validates that *max_len is large enough before
writing any data.
Fixes: be6e8dc0ba84 ("NFS support for btrfs - v3")
CC: stable@vger.kernel.org # 3.0+
Signed-off-by: Anderson Nascimento <anderson@allelesecurity.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/export.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c index 58b0f04d7123..6f81708658ae 100644 --- a/fs/btrfs/export.c +++ b/fs/btrfs/export.c @@ -22,7 +22,11 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, int type; if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) { - *max_len = BTRFS_FID_SIZE_CONNECTABLE; + if (btrfs_root_id(BTRFS_I(inode)->root) != + btrfs_root_id(BTRFS_I(parent)->root)) + *max_len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; + else + *max_len = BTRFS_FID_SIZE_CONNECTABLE; return FILEID_INVALID; } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) { *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE; @@ -44,6 +48,8 @@ static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, parent_root_id = BTRFS_I(parent)->root->root_key.objectid; if (parent_root_id != fid->root_objectid) { + if (*max_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) + return FILEID_INVALID; fid->parent_root_objectid = parent_root_id; len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; type = FILEID_BTRFS_WITH_PARENT_ROOT; |