From: Chao Yu <chao@kernel.org> To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu <chao@kernel.org>, stable@vger.kernel.org, syzbot+d015b6c2fbb5c383bf08@syzkaller.appspotmail.com Subject: [PATCH] f2fs: don't reset unchangable mount option in f2fs_remount() Date: Tue, 23 May 2023 11:58:22 +0800 [thread overview] Message-ID: <20230523035822.578123-1-chao@kernel.org> (raw) syzbot reports a bug as below: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN RIP: 0010:__lock_acquire+0x69/0x2000 kernel/locking/lockdep.c:4942 Call Trace: lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691 __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline] _raw_write_lock+0x2e/0x40 kernel/locking/spinlock.c:300 __drop_extent_tree+0x3ac/0x660 fs/f2fs/extent_cache.c:1100 f2fs_drop_extent_tree+0x17/0x30 fs/f2fs/extent_cache.c:1116 f2fs_insert_range+0x2d5/0x3c0 fs/f2fs/file.c:1664 f2fs_fallocate+0x4e4/0x6d0 fs/f2fs/file.c:1838 vfs_fallocate+0x54b/0x6b0 fs/open.c:324 ksys_fallocate fs/open.c:347 [inline] __do_sys_fallocate fs/open.c:355 [inline] __se_sys_fallocate fs/open.c:353 [inline] __x64_sys_fallocate+0xbd/0x100 fs/open.c:353 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The root cause is race condition as below: - since it tries to remount rw filesystem, so that do_remount won't call sb_prepare_remount_readonly to block fallocate, there may be race condition in between remount and fallocate. - in f2fs_remount(), default_options() will reset mount option to default one, and then update it based on result of parse_options(), so there is a hole which race condition can happen. Thread A Thread B - f2fs_fill_super - parse_options - clear_opt(READ_EXTENT_CACHE) - f2fs_remount - default_options - set_opt(READ_EXTENT_CACHE) - f2fs_fallocate - f2fs_insert_range - f2fs_drop_extent_tree - __drop_extent_tree - __may_extent_tree - test_opt(READ_EXTENT_CACHE) return true - write_lock(&et->lock) access NULL pointer - parse_options - clear_opt(READ_EXTENT_CACHE) Cc: <stable@vger.kernel.org> Reported-by: syzbot+d015b6c2fbb5c383bf08@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/20230522124203.3838360-1-chao@kernel.org Signed-off-by: Chao Yu <chao@kernel.org> --- fs/f2fs/super.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index aeed413cf5cd..96bf7e727175 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -2097,9 +2097,22 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root) return 0; } -static void default_options(struct f2fs_sb_info *sbi) +static void default_options(struct f2fs_sb_info *sbi, bool remount) { /* init some FS parameters */ + if (!remount) { + set_opt(sbi, READ_EXTENT_CACHE); + clear_opt(sbi, DISABLE_CHECKPOINT); + + if (f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) + set_opt(sbi, DISCARD); + + if (f2fs_sb_has_blkzoned(sbi)) + F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_SECTION; + else + F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_BLOCK; + } + if (f2fs_sb_has_readonly(sbi)) F2FS_OPTION(sbi).active_logs = NR_CURSEG_RO_TYPE; else @@ -2129,23 +2142,16 @@ static void default_options(struct f2fs_sb_info *sbi) set_opt(sbi, INLINE_XATTR); set_opt(sbi, INLINE_DATA); set_opt(sbi, INLINE_DENTRY); - set_opt(sbi, READ_EXTENT_CACHE); set_opt(sbi, NOHEAP); - clear_opt(sbi, DISABLE_CHECKPOINT); set_opt(sbi, MERGE_CHECKPOINT); F2FS_OPTION(sbi).unusable_cap = 0; sbi->sb->s_flags |= SB_LAZYTIME; if (!f2fs_is_readonly(sbi)) set_opt(sbi, FLUSH_MERGE); - if (f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) - set_opt(sbi, DISCARD); - if (f2fs_sb_has_blkzoned(sbi)) { + if (f2fs_sb_has_blkzoned(sbi)) F2FS_OPTION(sbi).fs_mode = FS_MODE_LFS; - F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_SECTION; - } else { + else F2FS_OPTION(sbi).fs_mode = FS_MODE_ADAPTIVE; - F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_BLOCK; - } #ifdef CONFIG_F2FS_FS_XATTR set_opt(sbi, XATTR_USER); @@ -2317,7 +2323,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data) clear_sbi_flag(sbi, SBI_NEED_SB_WRITE); } - default_options(sbi); + default_options(sbi, true); /* parse mount options */ err = parse_options(sb, data, true); @@ -4377,7 +4383,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) sbi->s_chksum_seed = f2fs_chksum(sbi, ~0, raw_super->uuid, sizeof(raw_super->uuid)); - default_options(sbi); + default_options(sbi, false); /* parse mount options */ options = kstrdup((const char *)data, GFP_KERNEL); if (data && !options) { -- 2.40.1
WARNING: multiple messages have this Message-ID (diff)
From: Chao Yu <chao@kernel.org> To: jaegeuk@kernel.org Cc: syzbot+d015b6c2fbb5c383bf08@syzkaller.appspotmail.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: [f2fs-dev] [PATCH] f2fs: don't reset unchangable mount option in f2fs_remount() Date: Tue, 23 May 2023 11:58:22 +0800 [thread overview] Message-ID: <20230523035822.578123-1-chao@kernel.org> (raw) syzbot reports a bug as below: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN RIP: 0010:__lock_acquire+0x69/0x2000 kernel/locking/lockdep.c:4942 Call Trace: lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691 __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline] _raw_write_lock+0x2e/0x40 kernel/locking/spinlock.c:300 __drop_extent_tree+0x3ac/0x660 fs/f2fs/extent_cache.c:1100 f2fs_drop_extent_tree+0x17/0x30 fs/f2fs/extent_cache.c:1116 f2fs_insert_range+0x2d5/0x3c0 fs/f2fs/file.c:1664 f2fs_fallocate+0x4e4/0x6d0 fs/f2fs/file.c:1838 vfs_fallocate+0x54b/0x6b0 fs/open.c:324 ksys_fallocate fs/open.c:347 [inline] __do_sys_fallocate fs/open.c:355 [inline] __se_sys_fallocate fs/open.c:353 [inline] __x64_sys_fallocate+0xbd/0x100 fs/open.c:353 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The root cause is race condition as below: - since it tries to remount rw filesystem, so that do_remount won't call sb_prepare_remount_readonly to block fallocate, there may be race condition in between remount and fallocate. - in f2fs_remount(), default_options() will reset mount option to default one, and then update it based on result of parse_options(), so there is a hole which race condition can happen. Thread A Thread B - f2fs_fill_super - parse_options - clear_opt(READ_EXTENT_CACHE) - f2fs_remount - default_options - set_opt(READ_EXTENT_CACHE) - f2fs_fallocate - f2fs_insert_range - f2fs_drop_extent_tree - __drop_extent_tree - __may_extent_tree - test_opt(READ_EXTENT_CACHE) return true - write_lock(&et->lock) access NULL pointer - parse_options - clear_opt(READ_EXTENT_CACHE) Cc: <stable@vger.kernel.org> Reported-by: syzbot+d015b6c2fbb5c383bf08@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/20230522124203.3838360-1-chao@kernel.org Signed-off-by: Chao Yu <chao@kernel.org> --- fs/f2fs/super.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index aeed413cf5cd..96bf7e727175 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -2097,9 +2097,22 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root) return 0; } -static void default_options(struct f2fs_sb_info *sbi) +static void default_options(struct f2fs_sb_info *sbi, bool remount) { /* init some FS parameters */ + if (!remount) { + set_opt(sbi, READ_EXTENT_CACHE); + clear_opt(sbi, DISABLE_CHECKPOINT); + + if (f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) + set_opt(sbi, DISCARD); + + if (f2fs_sb_has_blkzoned(sbi)) + F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_SECTION; + else + F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_BLOCK; + } + if (f2fs_sb_has_readonly(sbi)) F2FS_OPTION(sbi).active_logs = NR_CURSEG_RO_TYPE; else @@ -2129,23 +2142,16 @@ static void default_options(struct f2fs_sb_info *sbi) set_opt(sbi, INLINE_XATTR); set_opt(sbi, INLINE_DATA); set_opt(sbi, INLINE_DENTRY); - set_opt(sbi, READ_EXTENT_CACHE); set_opt(sbi, NOHEAP); - clear_opt(sbi, DISABLE_CHECKPOINT); set_opt(sbi, MERGE_CHECKPOINT); F2FS_OPTION(sbi).unusable_cap = 0; sbi->sb->s_flags |= SB_LAZYTIME; if (!f2fs_is_readonly(sbi)) set_opt(sbi, FLUSH_MERGE); - if (f2fs_hw_support_discard(sbi) || f2fs_hw_should_discard(sbi)) - set_opt(sbi, DISCARD); - if (f2fs_sb_has_blkzoned(sbi)) { + if (f2fs_sb_has_blkzoned(sbi)) F2FS_OPTION(sbi).fs_mode = FS_MODE_LFS; - F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_SECTION; - } else { + else F2FS_OPTION(sbi).fs_mode = FS_MODE_ADAPTIVE; - F2FS_OPTION(sbi).discard_unit = DISCARD_UNIT_BLOCK; - } #ifdef CONFIG_F2FS_FS_XATTR set_opt(sbi, XATTR_USER); @@ -2317,7 +2323,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data) clear_sbi_flag(sbi, SBI_NEED_SB_WRITE); } - default_options(sbi); + default_options(sbi, true); /* parse mount options */ err = parse_options(sb, data, true); @@ -4377,7 +4383,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) sbi->s_chksum_seed = f2fs_chksum(sbi, ~0, raw_super->uuid, sizeof(raw_super->uuid)); - default_options(sbi); + default_options(sbi, false); /* parse mount options */ options = kstrdup((const char *)data, GFP_KERNEL); if (data && !options) { -- 2.40.1 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
next reply other threads:[~2023-05-23 3:58 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-05-23 3:58 Chao Yu [this message] 2023-05-23 3:58 ` [f2fs-dev] [PATCH] f2fs: don't reset unchangable mount option in f2fs_remount() Chao Yu 2023-05-30 23:40 ` patchwork-bot+f2fs 2023-05-30 23:40 ` patchwork-bot+f2fs
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20230523035822.578123-1-chao@kernel.org \ --to=chao@kernel.org \ --cc=jaegeuk@kernel.org \ --cc=linux-f2fs-devel@lists.sourceforge.net \ --cc=linux-kernel@vger.kernel.org \ --cc=stable@vger.kernel.org \ --cc=syzbot+d015b6c2fbb5c383bf08@syzkaller.appspotmail.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.