kernel/git/stable/linux.git/fs/squashfs, branch linux-6.6.y

Squashfs: check block offset is not negative

2026-09-14T11:29:46+00:00

[ Upstream commit e300eb5002925b29be803d2661af07266cfa267e ] If a negative offset is read off disk (for example the offset into the decompressed fragment block), this will cause squashfs_copy_data() to perform an out of bounds access. Fix by checking if offset is negative, and returning 0. This matches existing behaviour where an offset beyond the block returns 0 bytes copied. To trigger this out of bounds access requires a crafted Squashfs filesystem and CAP_SYS_ADMIN to mount it. Unprivileged users will not be able to mount such a filesystem, but once mounted, an unprivileged user can trigger the out of bounds access by reading the crafted file with the negative offset. Link: https://lore.kernel.org/20260807162951.672510-1-phillip@squashfs.org.uk Fixes: f400e12656ab ("Squashfs: cache operations") Signed-off-by: Phillip Lougher Reported-by: Yuejie Shi Closes: https://lore.kernel.org/all/20260803032735.81785-1-syjcnss@gmail.com/ Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

Squashfs: check metadata block offset is within range

2026-03-25T10:05:37+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()

2025-10-19T14:30:57+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

2025-10-19T14:30:57+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

2025-10-15T09:58:07+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

2025-08-28T14:28:43+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

2025-06-19T13:28:23+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: sanity check symbolic link size

2024-09-12T09:11:39+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

Squashfs: fix variable overflow triggered by sysbot

2024-08-19T04:04:26+00:00

[ Upstream commit 12427de9439d68b8e96ba6f50b601ef15f437612 ] Sysbot reports a slab out of bounds write in squashfs_readahead(). This is ultimately caused by a file reporting an (infeasibly) large file size (1407374883553280 bytes) with the minimum block size of 4K. This causes variable overflow. Link: https://lkml.kernel.org/r/20231113160901.6444-1-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher Reported-by: syzbot+604424eb051c2f696163@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000b1fda20609ede0d1@google.com/ Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

squashfs: squashfs_read_data need to check if the length is 0

2024-08-19T04:04:26+00:00

[ Upstream commit eb66b8abae98f869c224f7c852b685ae02144564 ] When the length passed in is 0, the pagemap_scan_test_walk() caller should bail. This error causes at least a WARN_ON(). Link: https://lkml.kernel.org/r/20231116031352.40853-1-lizhi.xu@windriver.com Reported-by: syzbot+32d3767580a1ea339a81@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/0000000000000526f2060a30a085@google.com Signed-off-by: Lizhi Xu Reviewed-by: Phillip Lougher Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin