From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 22D6022AE68; Tue, 29 Apr 2025 17:52:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745949169; cv=none; b=GhdSyFktWqElOW7QHmlgsu0mizYeZ3phVQ6aj61MVSdwqppIcpygK4hKPRz6iY4MyxC97lU1GM5Gt9nCuyFjceliG33V8I0GdHZ2I1ihHPcRGaCEc5sGsdnidP8yI4mfPq5PPHPAHtxch/ODLyXvZfSigIzJ12MYCl0Ol0wx1xU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745949169; c=relaxed/simple; bh=EuPrxi6301D2lEbCfqthDvvgtQ+Ie8I7sky6gG+wi4U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hLY8jUtLeRrYYQD/o9EBrsOpejTMTYIQkMFyb6EIhGky48hufxGDl81w11JOvpbEZ381ONFVIKWdGXhYIqAKmQAziw5XtwmGFPMG8jO1uzf9+QPm7Ipaic8s02BfCMRIu80KwfvBhS+bBF+rfy9PmEOATOfjjpQ+X98G4MZSg8M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uXnrFhNH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="uXnrFhNH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9644C4CEE3; Tue, 29 Apr 2025 17:52:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1745949169; bh=EuPrxi6301D2lEbCfqthDvvgtQ+Ie8I7sky6gG+wi4U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uXnrFhNHKc1dKgdm4MXrZJec4PhRL+SJBgt7v/O8p3beWwutquIp2vp+UJKlEVpOC 6aKNoqhV/IhxM9fp+69cG+lEFSPH+pcBY60pUR/44CdvfetyDzFQy7i5HWYDxv3qV6 EZNyzkQm8PYaRaCtbd0zWBjQbzVYqgbHCg6lkGjo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiaxi Shen , Theodore Tso , stable@kernel.org, Xiangyu Chen , He Zhe , syzbot+59e0101c430934bc9a36@syzkaller.appspotmail.com Subject: [PATCH 5.15 234/373] ext4: fix timer use-after-free on failed mount Date: Tue, 29 Apr 2025 18:41:51 +0200 Message-ID: <20250429161132.766941121@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250429161123.119104857@linuxfoundation.org> References: <20250429161123.119104857@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiaxi Shen commit 0ce160c5bdb67081a62293028dc85758a8efb22a upstream. Syzbot has found an ODEBUG bug in ext4_fill_super The del_timer_sync function cancels the s_err_report timer, which reminds about filesystem errors daily. We should guarantee the timer is no longer active before kfree(sbi). When filesystem mounting fails, the flow goes to failed_mount3, where an error occurs when ext4_stop_mmpd is called, causing a read I/O failure. This triggers the ext4_handle_error function that ultimately re-arms the timer, leaving the s_err_report timer active before kfree(sbi) is called. Fix the issue by canceling the s_err_report timer after calling ext4_stop_mmpd. Signed-off-by: Xiaxi Shen Reported-and-tested-by: syzbot+59e0101c430934bc9a36@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=59e0101c430934bc9a36 Link: https://patch.msgid.link/20240715043336.98097-1-shenxiaxi26@gmail.com Signed-off-by: Theodore Ts'o Cc: stable@kernel.org [Minor context change fixed] Signed-off-by: Xiangyu Chen Signed-off-by: He Zhe Signed-off-by: Greg Kroah-Hartman --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5085,8 +5085,8 @@ failed_mount3a: failed_mount3: /* flush s_error_work before sbi destroy */ flush_work(&sbi->s_error_work); - del_timer_sync(&sbi->s_err_report); ext4_stop_mmpd(sbi); + del_timer_sync(&sbi->s_err_report); failed_mount2: rcu_read_lock(); group_desc = rcu_dereference(sbi->s_group_desc);