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| author | Theodore Ts'o <tytso@mit.edu> | 2009-11-23 07:24:46 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-11-23 07:24:46 -0500 |
| commit | 503358ae01b70ce6909d19dd01287093f6b6271c (patch) | |
| tree | ef81060e38e5eb0895e9455892d5f8cf186a0603 /fs | |
| parent | 2de770a406b06dfc619faabbf5d85c835ed3f2e1 (diff) | |
| download | blackbird-obmc-linux-503358ae01b70ce6909d19dd01287093f6b6271c.tar.gz blackbird-obmc-linux-503358ae01b70ce6909d19dd01287093f6b6271c.zip | |
ext4: avoid divide by zero when trying to mount a corrupted file system
If s_log_groups_per_flex is greater than 31, then groups_per_flex will
will overflow and cause a divide by zero error. This can cause kernel
BUG if such a file system is mounted.
Thanks to Nageswara R Sastry for analyzing the failure and providing
an initial patch.
http://bugzilla.kernel.org/show_bug.cgi?id=14287
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/super.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index d4ca92aab514..8662b2e6e9f9 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1673,14 +1673,14 @@ static int ext4_fill_flex_info(struct super_block *sb) size_t size; int i; - if (!sbi->s_es->s_log_groups_per_flex) { + sbi->s_log_groups_per_flex = sbi->s_es->s_log_groups_per_flex; + groups_per_flex = 1 << sbi->s_log_groups_per_flex; + + if (groups_per_flex < 2) { sbi->s_log_groups_per_flex = 0; return 1; } - sbi->s_log_groups_per_flex = sbi->s_es->s_log_groups_per_flex; - groups_per_flex = 1 << sbi->s_log_groups_per_flex; - /* We allocate both existing and potentially added groups */ flex_group_count = ((sbi->s_groups_count + groups_per_flex - 1) + ((le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) + 1) << |
