kernel/linux.git/fs/squashfs, branch v5.15.208

Squashfs: check metadata block offset is within range

2026-04-18T08:33:09+00:00

commit fdb24a820a5832ec4532273282cbd4f22c291a0d upstream. Syzkaller reports a "general protection fault in squashfs_copy_data" This is ultimately caused by a corrupted index look-up table, which produces a negative metadata block offset. This is subsequently passed to squashfs_copy_data (via squashfs_read_metadata) where the negative offset causes an out of bounds access. The fix is to check that the offset is within range in squashfs_read_metadata. This will trap this and other cases. Link: https://lkml.kernel.org/r/20260217050955.138351-1-phillip@squashfs.org.uk Fixes: f400e12656ab ("Squashfs: cache operations") Reported-by: syzbot+a9747fe1c35a5b115d3f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/699234e2.a70a0220.2c38d7.00e2.GAE@google.com/ Signed-off-by: Phillip Lougher Cc: Christian Brauner Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

Squashfs: reject negative file sizes in squashfs_read_inode()

2025-10-19T14:21:50+00:00

[ Upstream commit 9f1c14c1de1bdde395f6cc893efa4f80a2ae3b2b ] Syskaller reports a "WARNING in ovl_copy_up_file" in overlayfs. This warning is ultimately caused because the underlying Squashfs file system returns a file with a negative file size. This commit checks for a negative file size and returns EINVAL. [phillip@squashfs.org.uk: only need to check 64 bit quantity] Link: https://lkml.kernel.org/r/20250926222305.110103-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20250926215935.107233-1-phillip@squashfs.org.uk Fixes: 6545b246a2c8 ("Squashfs: inode operations") Signed-off-by: Phillip Lougher Reported-by: syzbot+f754e01116421e9754b9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68d580e5.a00a0220.303701.0019.GAE@google.com/ Cc: Amir Goldstein Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Squashfs: add additional inode sanity checking

2025-10-19T14:21:50+00:00

[ Upstream commit 9ee94bfbe930a1b39df53fa2d7b31141b780eb5a ] Patch series "Squashfs: performance improvement and a sanity check". This patchset adds an additional sanity check when reading regular file inodes, and adds support for SEEK_DATA/SEEK_HOLE lseek() whence values. This patch (of 2): Add an additional sanity check when reading regular file inodes. A regular file if the file size is an exact multiple of the filesystem block size cannot have a fragment. This is because by definition a fragment block stores tailends which are not a whole block in size. Link: https://lkml.kernel.org/r/20250923220652.568416-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20250923220652.568416-2-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton Stable-dep-of: 9f1c14c1de1b ("Squashfs: reject negative file sizes in squashfs_read_inode()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Squashfs: fix uninit-value in squashfs_get_parent

2025-10-19T14:21:38+00:00

commit 74058c0a9fc8b2b4d5f4a0ef7ee2cfa66a9e49cf upstream. Syzkaller reports a "KMSAN: uninit-value in squashfs_get_parent" bug. This is caused by open_by_handle_at() being called with a file handle containing an invalid parent inode number. In particular the inode number is that of a symbolic link, rather than a directory. Squashfs_get_parent() gets called with that symbolic link inode, and accesses the parent member field. unsigned int parent_ino = squashfs_i(inode)->parent; Because non-directory inodes in Squashfs do not have a parent value, this is uninitialised, and this causes an uninitialised value access. The fix is to initialise parent with the invalid inode 0, which will cause an EINVAL error to be returned. Regular inodes used to share the parent field with the block_list_start field. This is removed in this commit to enable the parent field to contain the invalid inode number 0. Link: https://lkml.kernel.org/r/20250918233308.293861-1-phillip@squashfs.org.uk Fixes: 122601408d20 ("Squashfs: export operations") Signed-off-by: Phillip Lougher Reported-by: syzbot+157bdef5cf596ad0da2c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68cc2431.050a0220.139b6.0001.GAE@google.com/ Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

squashfs: fix memory leak in squashfs_fill_super

2025-08-28T14:24:34+00:00

commit b64700d41bdc4e9f82f1346c15a3678ebb91a89c upstream. If sb_min_blocksize returns 0, squashfs_fill_super exits without freeing allocated memory (sb->s_fs_info). Fix this by moving the call to sb_min_blocksize to before memory is allocated. Link: https://lkml.kernel.org/r/20250811223740.110392-1-phillip@squashfs.org.uk Fixes: 734aa85390ea ("Squashfs: check return result of sb_min_blocksize") Signed-off-by: Phillip Lougher Reported-by: Scott GUO Closes: https://lore.kernel.org/all/20250811061921.3807353-1-scott_gzh@163.com Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

Squashfs: check return result of sb_min_blocksize

2025-06-27T10:05:14+00:00

[ Upstream commit 734aa85390ea693bb7eaf2240623d41b03705c84 ] Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug. Syzkaller forks multiple processes which after mounting the Squashfs filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000). Now if this ioctl occurs at the same time another process is in the process of mounting a Squashfs filesystem on /dev/loop0, the failure occurs. When this happens the following code in squashfs_fill_super() fails. ---- msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize); ---- sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0. As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2 is set to 64. This subsequently causes the UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long') This commit adds a check for a 0 return by sb_min_blocksize(). Link: https://lkml.kernel.org/r/20250409024747.876480-1-phillip@squashfs.org.uk Fixes: 0aa666190509 ("Squashfs: super block operations") Reported-by: syzbot+65761fc25a137b9c8c6e@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67f0dd7a.050a0220.0a13.0230.GAE@google.com/ Signed-off-by: Phillip Lougher Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

Squashfs: check the inode number is not the invalid value of zero

2025-03-13T11:51:09+00:00

commit 9253c54e01b6505d348afbc02abaa4d9f8a01395 upstream. Syskiller has produced an out of bounds access in fill_meta_index(). That out of bounds access is ultimately caused because the inode has an inode number with the invalid value of zero, which was not checked. The reason this causes the out of bounds access is due to following sequence of events: 1. Fill_meta_index() is called to allocate (via empty_meta_index()) and fill a metadata index. It however suffers a data read error and aborts, invalidating the newly returned empty metadata index. It does this by setting the inode number of the index to zero, which means unused (zero is not a valid inode number). 2. When fill_meta_index() is subsequently called again on another read operation, locate_meta_index() returns the previous index because it matches the inode number of 0. Because this index has been returned it is expected to have been filled, and because it hasn't been, an out of bounds access is performed. This patch adds a sanity check which checks that the inode number is not zero when the inode is created and returns -EINVAL if it is. [phillip@squashfs.org.uk: whitespace fix] Link: https://lkml.kernel.org/r/20240409204723.446925-1-phillip@squashfs.org.uk Link: https://lkml.kernel.org/r/20240408220206.435788-1-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Reported-by: "Ubisectech Sirius" Closes: https://lore.kernel.org/lkml/87f5c007-b8a5-41ae-8b57-431e924c5915.bugreport@ubisectech.com/ Cc: Christian Brauner Cc: Signed-off-by: Andrew Morton Signed-off-by: Xiangyu Chen Signed-off-by: He Zhe Signed-off-by: Greg Kroah-Hartman

Squashfs: sanity check symbolic link size

2024-09-12T09:07:50+00:00

[ Upstream commit 810ee43d9cd245d138a2733d87a24858a23f577d ] Syzkiller reports a "KMSAN: uninit-value in pick_link" bug. This is caused by an uninitialised page, which is ultimately caused by a corrupted symbolic link size read from disk. The reason why the corrupted symlink size causes an uninitialised page is due to the following sequence of events: 1. squashfs_read_inode() is called to read the symbolic link from disk. This assigns the corrupted value 3875536935 to inode->i_size. 2. Later squashfs_symlink_read_folio() is called, which assigns this corrupted value to the length variable, which being a signed int, overflows producing a negative number. 3. The following loop that fills in the page contents checks that the copied bytes is less than length, which being negative means the loop is skipped, producing an uninitialised page. This patch adds a sanity check which checks that the symbolic link size is not larger than expected. -- Signed-off-by: Phillip Lougher Link: https://lore.kernel.org/r/20240811232821.13903-1-phillip@squashfs.org.uk Reported-by: Lizhi Xu Reported-by: syzbot+24ac24ff58dc5b0d26b9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000a90e8c061e86a76b@google.com/ V2: fix spelling mistake. Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

revert "squashfs: harden sanity check in squashfs_read_xattr_id_table"

2023-02-22T11:57:07+00:00

commit a5b21d8d791cd4db609d0bbcaa9e0c7e019888d1 upstream. This fix was nacked by Philip, for reasons identified in the email linked below. Link: https://lkml.kernel.org/r/68f15d67-8945-2728-1f17-5b53a80ec52d@squashfs.org.uk Fixes: 72e544b1b28325 ("squashfs: harden sanity check in squashfs_read_xattr_id_table") Cc: Alexey Khoroshilov Cc: Fedor Pchelkin Cc: Phillip Lougher Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

Squashfs: fix handling and sanity checking of xattr_ids count

2023-02-09T10:26:45+00:00

commit f65c4bbbd682b0877b669828b4e033b8d5d0a2dc upstream. A Sysbot [1] corrupted filesystem exposes two flaws in the handling and sanity checking of the xattr_ids count in the filesystem. Both of these flaws cause computation overflow due to incorrect typing. In the corrupted filesystem the xattr_ids value is 4294967071, which stored in a signed variable becomes the negative number -225. Flaw 1 (64-bit systems only): The signed integer xattr_ids variable causes sign extension. This causes variable overflow in the SQUASHFS_XATTR_*(A) macros. The variable is first multiplied by sizeof(struct squashfs_xattr_id) where the type of the sizeof operator is "unsigned long". On a 64-bit system this is 64-bits in size, and causes the negative number to be sign extended and widened to 64-bits and then become unsigned. This produces the very large number 18446744073709548016 or 2^64 - 3600. This number when rounded up by SQUASHFS_METADATA_SIZE - 1 (8191 bytes) and divided by SQUASHFS_METADATA_SIZE overflows and produces a length of 0 (stored in len). Flaw 2 (32-bit systems only): On a 32-bit system the integer variable is not widened by the unsigned long type of the sizeof operator (32-bits), and the signedness of the variable has no effect due it always being treated as unsigned. The above corrupted xattr_ids value of 4294967071, when multiplied overflows and produces the number 4294963696 or 2^32 - 3400. This number when rounded up by SQUASHFS_METADATA_SIZE - 1 (8191 bytes) and divided by SQUASHFS_METADATA_SIZE overflows again and produces a length of 0. The effect of the 0 length computation: In conjunction with the corrupted xattr_ids field, the filesystem also has a corrupted xattr_table_start value, where it matches the end of filesystem value of 850. This causes the following sanity check code to fail because the incorrectly computed len of 0 matches the incorrect size of the table reported by the superblock (0 bytes). len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids); indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids); /* * The computed size of the index table (len bytes) should exactly * match the table start and end points */ start = table_start + sizeof(*id_table); end = msblk->bytes_used; if (len != (end - start)) return ERR_PTR(-EINVAL); Changing the xattr_ids variable to be "usigned int" fixes the flaw on a 64-bit system. This relies on the fact the computation is widened by the unsigned long type of the sizeof operator. Casting the variable to u64 in the above macro fixes this flaw on a 32-bit system. It also means 64-bit systems do not implicitly rely on the type of the sizeof operator to widen the computation. [1] https://lore.kernel.org/lkml/000000000000cd44f005f1a0f17f@google.com/ Link: https://lkml.kernel.org/r/20230127061842.10965-1-phillip@squashfs.org.uk Fixes: 506220d2ba21 ("squashfs: add more sanity checks in xattr id lookup") Signed-off-by: Phillip Lougher Reported-by: Cc: Alexey Khoroshilov Cc: Fedor Pchelkin Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman