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Message-Id: <20240328143301.6432-1-mish.uxin2012@yandex.ru>
Date: Thu, 28 Mar 2024 17:33:01 +0300
From: Mikhail Ukhin <mish.uxin2012@...dex.ru>
To: "Theodore Ts'o" <tytso@....edu>
Cc: Mikhail Ukhin <mish.uxin2012@...dex.ru>,
Andreas Dilger <adilger.kernel@...ger.ca>,
linux-ext4@...r.kernel.org,
linux-kernel@...r.kernel.org,
Michail Ivanov <iwanov-23@...ru>,
Pavel Koshutin <koshutin.pavel@...dex.ru>,
Artem Sadovnikov <ancowi69@...il.com>
Subject: [PATCH] ext4: fix semaphore unlocking order
Fuzzing reports a possible deadlock in jbd2_log_wait_commit.
The problem occurs in ext4_ind_migrate due to an incorrect order of
unlocking of the journal and write semaphores - the order of unlocking
must be the reverse of the order of locking.
Found by Linux Verification Center (linuxtesting.org) with syzkaller.
Signed-off-by: Artem Sadovnikov <ancowi69@...il.com>
---
fs/ext4/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index d98ac2af8199..a5e1492bbaaa 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -663,8 +663,8 @@ int ext4_ind_migrate(struct inode *inode)
if (unlikely(ret2 && !ret))
ret = ret2;
errout:
- ext4_journal_stop(handle);
up_write(&EXT4_I(inode)->i_data_sem);
+ ext4_journal_stop(handle);
out_unlock:
ext4_writepages_up_write(inode->i_sb, alloc_ctx);
return ret;
--
2.25.1
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