[Devel] [PATCH RHEL7 COMMIT] ext4: fix out of bounds access in ext4_alloc_group_desc_bh_array()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-862.9.1.vz7.70.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-862.9.1.vz7.70.1
------>
commit 5bb34796595cdba1caa7bad6a172cdc468bd9562
Author: Jan Dakinevich <jan.dakinevich at virtuozzo.com>
Date:   Mon Aug 13 14:00:31 2018 +0300

    ext4: fix out of bounds access in ext4_alloc_group_desc_bh_array()
    
    https://jira.sw.ru/browse/PSBM-87413
    Fixes: d695abe ("ext4: replace ext4_kvmalloc() with kvmalloc()")
    Signed-off-by: Jan Dakinevich <jan.dakinevich at virtuozzo.com>
---
 fs/ext4/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 94c904f72af6..16a69d853c28 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2192,7 +2192,7 @@ int ext4_alloc_group_desc_bh_array(struct super_block *sb, ext4_group_t ngroup)
 	}
 
 	memcpy(n_group_desc, sbi->s_group_desc,
-	       num_desc * sizeof(struct buffer_head *));
+	       sbi->s_gdb_count * sizeof(struct buffer_head *));
 	kvfree(sbi->s_group_desc);
 
 	sbi->s_group_desc = n_group_desc;