kernel/linux.git/fs/ext4/super.c, branch v6.4

Revert "ext4: don't clear SB_RDONLY when remounting r/w until quota is re-enabled"

2023-06-08T13:57:04+00:00

This reverts commit a44be64bbecb15a452496f60db6eacfee2b59c79. Link: https://lore.kernel.org/r/653b3359-2005-21b1-039d-c55ca4cffdcc@gmail.com Signed-off-by: Theodore Ts'o

ext4: enable the lazy init thread when remounting read/write

2023-05-30T19:33:57+00:00

In commit a44be64bbecb ("ext4: don't clear SB_RDONLY when remounting r/w until quota is re-enabled") we defer clearing tyhe SB_RDONLY flag in struct super. However, we didn't defer when we checked sb_rdonly() to determine the lazy itable init thread should be enabled, with the next result that the lazy inode table initialization would not be properly started. This can cause generic/231 to fail in ext4's nojournal mode. Fix this by moving when we decide to start or stop the lazy itable init thread to after we clear the SB_RDONLY flag when we are remounting the file system read/write. Fixes a44be64bbecb ("ext4: don't clear SB_RDONLY when remounting r/w until...") Signed-off-by: Theodore Ts'o Link: https://lore.kernel.org/r/20230527035729.1001605-1-tytso@mit.edu Signed-off-by: Theodore Ts'o

ext4: add indication of ro vs r/w mounts in the mount message

2023-05-13T22:05:05+00:00

Whether the file system is mounted read-only or read/write is more important than the quota mode, which we are already printing. Add the ro vs r/w indication since this can be helpful in debugging problems from the console log. Signed-off-by: Theodore Ts'o

ext4: improve error recovery code paths in __ext4_remount()

2023-05-13T22:05:05+00:00

If there are failures while changing the mount options in __ext4_remount(), we need to restore the old mount options. This commit fixes two problem. The first is there is a chance that we will free the old quota file names before a potential failure leading to a use-after-free. The second problem addressed in this commit is if there is a failed read/write to read-only transition, if the quota has already been suspended, we need to renable quota handling. Cc: stable@kernel.org Link: https://lore.kernel.org/r/20230506142419.984260-2-tytso@mit.edu Signed-off-by: Theodore Ts'o

ext4: don't clear SB_RDONLY when remounting r/w until quota is re-enabled

2023-05-13T22:05:05+00:00

When a file system currently mounted read/only is remounted read/write, if we clear the SB_RDONLY flag too early, before the quota is initialized, and there is another process/thread constantly attempting to create a directory, it's possible to trigger the WARN_ON_ONCE(dquot_initialize_needed(inode)); in ext4_xattr_block_set(), with the following stack trace: WARNING: CPU: 0 PID: 5338 at fs/ext4/xattr.c:2141 ext4_xattr_block_set+0x2ef2/0x3680 RIP: 0010:ext4_xattr_block_set+0x2ef2/0x3680 fs/ext4/xattr.c:2141 Call Trace: ext4_xattr_set_handle+0xcd4/0x15c0 fs/ext4/xattr.c:2458 ext4_initxattrs+0xa3/0x110 fs/ext4/xattr_security.c:44 security_inode_init_security+0x2df/0x3f0 security/security.c:1147 __ext4_new_inode+0x347e/0x43d0 fs/ext4/ialloc.c:1324 ext4_mkdir+0x425/0xce0 fs/ext4/namei.c:2992 vfs_mkdir+0x29d/0x450 fs/namei.c:4038 do_mkdirat+0x264/0x520 fs/namei.c:4061 __do_sys_mkdirat fs/namei.c:4076 [inline] __se_sys_mkdirat fs/namei.c:4074 [inline] __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4074 Cc: stable@kernel.org Link: https://lore.kernel.org/r/20230506142419.984260-1-tytso@mit.edu Reported-by: syzbot+6385d7d3065524c5ca6d@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=6513f6cb5cd6b5fc9f37e3bb70d273b94be9c34c Signed-off-by: Theodore Ts'o

ext4: avoid a potential slab-out-of-bounds in ext4_group_desc_csum

2023-05-13T22:05:04+00:00

When modifying the block device while it is mounted by the filesystem, syzbot reported the following: BUG: KASAN: slab-out-of-bounds in crc16+0x206/0x280 lib/crc16.c:58 Read of size 1 at addr ffff888075f5c0a8 by task syz-executor.2/15586 CPU: 1 PID: 15586 Comm: syz-executor.2 Not tainted 6.2.0-rc5-syzkaller-00205-gc96618275234 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106 print_address_description+0x74/0x340 mm/kasan/report.c:306 print_report+0x107/0x1f0 mm/kasan/report.c:417 kasan_report+0xcd/0x100 mm/kasan/report.c:517 crc16+0x206/0x280 lib/crc16.c:58 ext4_group_desc_csum+0x81b/0xb20 fs/ext4/super.c:3187 ext4_group_desc_csum_set+0x195/0x230 fs/ext4/super.c:3210 ext4_mb_clear_bb fs/ext4/mballoc.c:6027 [inline] ext4_free_blocks+0x191a/0x2810 fs/ext4/mballoc.c:6173 ext4_remove_blocks fs/ext4/extents.c:2527 [inline] ext4_ext_rm_leaf fs/ext4/extents.c:2710 [inline] ext4_ext_remove_space+0x24ef/0x46a0 fs/ext4/extents.c:2958 ext4_ext_truncate+0x177/0x220 fs/ext4/extents.c:4416 ext4_truncate+0xa6a/0xea0 fs/ext4/inode.c:4342 ext4_setattr+0x10c8/0x1930 fs/ext4/inode.c:5622 notify_change+0xe50/0x1100 fs/attr.c:482 do_truncate+0x200/0x2f0 fs/open.c:65 handle_truncate fs/namei.c:3216 [inline] do_open fs/namei.c:3561 [inline] path_openat+0x272b/0x2dd0 fs/namei.c:3714 do_filp_open+0x264/0x4f0 fs/namei.c:3741 do_sys_openat2+0x124/0x4e0 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_sys_creat fs/open.c:1402 [inline] __se_sys_creat fs/open.c:1396 [inline] __x64_sys_creat+0x11f/0x160 fs/open.c:1396 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f72f8a8c0c9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f72f97e3168 EFLAGS: 00000246 ORIG_RAX: 0000000000000055 RAX: ffffffffffffffda RBX: 00007f72f8bac050 RCX: 00007f72f8a8c0c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000280 RBP: 00007f72f8ae7ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd165348bf R14: 00007f72f97e3300 R15: 0000000000022000 Replace le16_to_cpu(sbi->s_es->s_desc_size) with sbi->s_desc_size It reduces ext4's compiled text size, and makes the code more efficient (we remove an extra indirect reference and a potential byte swap on big endian systems), and there is no downside. It also avoids the potential KASAN / syzkaller failure, as a bonus. Reported-by: syzbot+fc51227e7100c9294894@syzkaller.appspotmail.com Reported-by: syzbot+8785e41224a3afd04321@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=70d28d11ab14bd7938f3e088365252aa923cff42 Link: https://syzkaller.appspot.com/bug?id=b85721b38583ecc6b5e72ff524c67302abbc30f3 Link: https://lore.kernel.org/all/000000000000ece18705f3b20934@google.com/ Fixes: 717d50e4971b ("Ext4: Uninitialized Block Groups") Cc: stable@vger.kernel.org Signed-off-by: Tudor Ambarus Link: https://lore.kernel.org/r/20230504121525.3275886-1-tudor.ambarus@linaro.org Signed-off-by: Theodore Ts'o

ext4: allow ext4_get_group_info() to fail

2023-05-13T22:02:46+00:00

Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device. For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL. Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k. Cc: stable@kernel.org Link: https://lore.kernel.org/r/20230430154311.579720-2-tytso@mit.edu Reported-by: syzbot+e2efa3efc15a1c9e95c3@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=69b28112e098b070f639efb356393af3ffec4220 Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara

Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2023-05-01T18:00:04+00:00

Pull ext4 fixes from Ted Ts'o: "Some ext4 regression and bug fixes" * tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: ext4: clean up error handling in __ext4_fill_super() ext4: reflect error codes from ext4_multi_mount_protect() to its callers ext4: fix lost error code reporting in __ext4_fill_super() ext4: fix unused iterator variable warnings ext4: fix use-after-free read in ext4_find_extent for bigalloc + inline ext4: fix i_disksize exceeding i_size problem in paritally written case

ext4: clean up error handling in __ext4_fill_super()

2023-04-28T16:56:40+00:00

There were two ways to return an error code; one was via setting the 'err' variable, and the second, if err was zero, was via the 'ret' variable. This was both confusing and fragile, and when code was factored out of __ext4_fill_super(), some of the error codes returned by the original code was replaced by -EINVAL, and in one case, the error code was placed by 0, triggering a kernel null pointer dereference. Clean this up by removing the 'ret' variable, leaving only one way to set the error code to be returned, and restore the errno codes that were returned via the the mount system call as they were before we started refactoring __ext4_fill_super(). Signed-off-by: Theodore Ts'o Reviewed-by: Jason Yan

ext4: reflect error codes from ext4_multi_mount_protect() to its callers

2023-04-28T16:56:40+00:00

This will allow more fine-grained errno codes to be returned by the mount system call. Cc: Andreas Dilger Signed-off-by: Theodore Ts'o