lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 10 Jan 2022 08:22:58 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Yi Zhuang <zhuangyi1@...wei.com>, Chao Yu <chao@...nel.org>, Jaegeuk Kim <jaegeuk@...nel.org> Subject: [PATCH 5.10 01/43] f2fs: quota: fix potential deadlock From: Chao Yu <chao@...nel.org> commit a5c0042200b28fff3bde6fa128ddeaef97990f8d upstream. As Yi Zhuang reported in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=214299 There is potential deadlock during quota data flush as below: Thread A: Thread B: f2fs_dquot_acquire down_read(&sbi->quota_sem) f2fs_write_checkpoint block_operations f2fs_look_all down_write(&sbi->cp_rwsem) f2fs_quota_write f2fs_write_begin __do_map_lock f2fs_lock_op down_read(&sbi->cp_rwsem) __need_flush_qutoa down_write(&sbi->quota_sem) This patch changes block_operations() to use trylock, if it fails, it means there is potential quota data updater, in this condition, let's flush quota data first and then trylock again to check dirty status of quota data. The side effect is: in heavy race condition (e.g. multi quota data upaters vs quota data flusher), it may decrease the probability of synchronizing quota data successfully in checkpoint() due to limited retry time of quota flush. Reported-by: Yi Zhuang <zhuangyi1@...wei.com> Signed-off-by: Chao Yu <chao@...nel.org> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/f2fs/checkpoint.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/f2fs/checkpoint.c +++ b/fs/f2fs/checkpoint.c @@ -1147,7 +1147,8 @@ static bool __need_flush_quota(struct f2 if (!is_journalled_quota(sbi)) return false; - down_write(&sbi->quota_sem); + if (!down_write_trylock(&sbi->quota_sem)) + return true; if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) { ret = false; } else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) {
Powered by blists - more mailing lists