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Message-Id: <1382002073-27862-1-git-send-email-guaneryu@gmail.com> Date: Thu, 17 Oct 2013 17:27:53 +0800 From: Eryu Guan <guaneryu@...il.com> To: linux-ext4@...r.kernel.org Cc: Eryu Guan <guaneryu@...il.com>, "Theodore Ts'o" <tytso@....edu> Subject: [PATCH] ext4: don't cache out of order extents A corrupted ext4 may have out of order leaf extents, i.e. extent: lblk 0--1023, len 1024, pblk 9217, flags: LEAF UNINIT extent: lblk 1000--2047, len 1024, pblk 10241, flags: LEAF UNINIT ^^^^ overlap with previous extent Reading such extent could hit BUG_ON() in ext4_es_cache_extent(). BUG_ON(end < lblk); The problem is that __read_extent_tree_block() tries to cache holes as well but assumes 'lblk' is greater than 'prev' and passes underflowed length to ext4_es_cache_extent(). I hit this when fuzz testing ext4, and am able to reproduce it by modifying the on-disk extent by hand. Ran xfstests on patched ext4 and no regression. Cc: "Theodore Ts'o" <tytso@....edu> Signed-off-by: Eryu Guan <guaneryu@...il.com> --- fs/ext4/extents.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 54d52af..c9ebcb9 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -503,7 +503,7 @@ __read_extent_tree_block(const char *function, unsigned int line, ext4_lblk_t lblk = le32_to_cpu(ex->ee_block); int len = ext4_ext_get_actual_len(ex); - if (prev && (prev != lblk)) + if (prev && (prev < lblk)) ext4_es_cache_extent(inode, prev, lblk - prev, ~0, EXTENT_STATUS_HOLE); -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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