linux-kernel - Re: [syzbot] task hung in exfat_write

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Message-ID: <000000000000884543060b5aa428@google.com>
Date:   Thu, 30 Nov 2023 00:43:15 -0800
From:   syzbot <syzbot+2f73ed585f115e98aee8@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org
Subject: Re: [syzbot] task hung in exfat_write_inode

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***

Subject: task hung in exfat_write_inode
Author: lizhi.xu@...driver.com

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f9ff5644bcc0

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index bfdfafe00993..4bdcdf126a21 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -132,14 +132,18 @@ int __exfat_truncate(struct inode *inode)
 			clu.dir += num_clusters;
 			clu.size -= num_clusters;
 		} else {
+			mutex_unlock(&sbi->s_lock);
 			while (num_clusters > 0) {
 				last_clu = clu.dir;
+				mutex_lock(&sbi->s_lock);
 				if (exfat_get_next_cluster(sb, &(clu.dir)))
 					return -EIO;
+				mutex_unlock(&sbi->s_lock);
 
 				num_clusters--;
 				clu.size--;
 			}
+			mutex_lock(&sbi->s_lock);
 		}
 	} else {
 		ei->flags = ALLOC_NO_FAT_CHAIN;