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From: OGAWA Hirofumi <>
To: Anatoly Trosinenko <>
Cc: Andrew Morton <>,
Subject: Re: PROBLEM: [kernel BUG at fs/fat/inode.c:162] when writing to a broken VFAT
Date: Sat, 02 Jun 2018 20:19:28 +0900	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <> (Anatoly Trosinenko's message of "Fri, 1 Jun 2018 12:45:14 +0300")

Anatoly Trosinenko <> writes:

> Description:
> Writing to some file on a broken VFAT partition causes kernel bug

Thanks. This patch should fix this issue.
OGAWA Hirofumi <>

[PATCH] fat: Use fat_fs_error() instead of BUG_ON() in __fat_get_block()

If file size and FAT cluster chain is not matched (corrupted image),
we can hit BUG_ON(!phys) in __fat_get_block().

So, use fat_fs_error() instead.

Signed-off-by: OGAWA Hirofumi <>

 fs/fat/inode.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff -puN fs/fat/inode.c~vfat-dont-bugon fs/fat/inode.c
--- linux/fs/fat/inode.c~vfat-dont-bugon	2018-06-02 20:15:04.441920069 +0900
+++ linux-hirofumi/fs/fat/inode.c	2018-06-02 20:15:04.442920067 +0900
@@ -158,8 +158,13 @@ static inline int __fat_get_block(struct
 	err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
 	if (err)
 		return err;
+	if (!phys) {
+		fat_fs_error(sb,
+			     "invalid FAT chain (i_pos %lld, last_block %ld)",
+			     MSDOS_I(inode)->i_pos, last_block);
+		return -EIO;
+	}
-	BUG_ON(!phys);
 	BUG_ON(*max_blocks != mapped_blocks);
 	map_bh(bh_result, sb, phys);

  reply	other threads:[~2018-06-02 11:40 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-01  9:45 PROBLEM: [kernel BUG at fs/fat/inode.c:162] when writing to a broken VFAT Anatoly Trosinenko
2018-06-02 11:19 ` OGAWA Hirofumi [this message]
2018-06-03 13:46   ` Anatoly Trosinenko

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