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| author | Theodore Ts'o <tytso@mit.edu> | 2023-05-05 22:20:29 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2023-05-13 18:05:05 -0400 |
| commit | 4c0b4818b1f636bc96359f7817a2d8bab6370162 (patch) | |
| tree | fab933e7b6fadc2a7c08b70718704416fd96da04 | |
| parent | 4b3cb1d108bfc2aebb0d7c8a52261a53cf7f5786 (diff) | |
| download | lwn-4c0b4818b1f636bc96359f7817a2d8bab6370162.tar.gz lwn-4c0b4818b1f636bc96359f7817a2d8bab6370162.zip | |
ext4: improve error recovery code paths in __ext4_remount()
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 <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/super.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c7bc4a2709cc..bc0b4a98b337 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -6617,9 +6617,6 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb) } #ifdef CONFIG_QUOTA - /* Release old quota file names */ - for (i = 0; i < EXT4_MAXQUOTAS; i++) - kfree(old_opts.s_qf_names[i]); if (enable_quota) { if (sb_any_quota_suspended(sb)) dquot_resume(sb, -1); @@ -6629,6 +6626,9 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb) goto restore_opts; } } + /* Release old quota file names */ + for (i = 0; i < EXT4_MAXQUOTAS; i++) + kfree(old_opts.s_qf_names[i]); #endif if (!test_opt(sb, BLOCK_VALIDITY) && sbi->s_system_blks) ext4_release_system_zone(sb); @@ -6642,6 +6642,13 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb) return 0; restore_opts: + /* + * If there was a failing r/w to ro transition, we may need to + * re-enable quota + */ + if ((sb->s_flags & SB_RDONLY) && !(old_sb_flags & SB_RDONLY) && + sb_any_quota_suspended(sb)) + dquot_resume(sb, -1); sb->s_flags = old_sb_flags; sbi->s_mount_opt = old_opts.s_mount_opt; sbi->s_mount_opt2 = old_opts.s_mount_opt2; |