diff options
| author | Theodore Ts'o <tytso@mit.edu> | 2009-11-23 07:24:46 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-12-14 08:07:23 -0800 |
| commit | a7aaaff940e284035a16e07cf90424da386ddce1 (patch) | |
| tree | 6d814aefa4560b1d3e7e93ba1987b7b7a7356a49 | |
| parent | 37bd334da00d116dba0526292891b1b572f1955b (diff) | |
ext4: avoid divide by zero when trying to mount a corrupted file system
(cherry picked from commit 503358ae01b70ce6909d19dd01287093f6b6271c)
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -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 667e672e58c..bc9e02a3609 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1695,14 +1695,14 @@ 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) << |