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authorTheodore Ts'o <tytso@mit.edu>2009-07-13 09:45:52 -0400
committerTheodore Ts'o <tytso@mit.edu>2009-07-13 09:45:52 -0400
commit833576b362e15c38be3bfe43942cda693e56287c (patch)
tree5a221bd167ae7f1b0575fd24fbc5e4cdae18a598
parentac046f1d6121ccdda6db66bd88acd52418f489b2 (diff)
downloadlinux-sh-833576b362e15c38be3bfe43942cda693e56287c.tar.gz
ext4: Fix ext4_mb_initialize_context() to initialize all fields
Pavel Roskin pointed out that kmemcheck indicated that ext4_mb_store_history() was accessing uninitialized values of ac->ac_tail and ac->ac_buddy leading to garbage in the mballoc history. Fix this by initializing the entire structure to all zeros first. Also, two fields were getting doubly initialized by the caller of ext4_mb_initialize_context, so remove them for efficiency's sake. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--fs/ext4/mballoc.c20
1 files changed, 2 insertions, 18 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 2fcaf286f1de..cd258463e2a9 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4227,14 +4227,9 @@ ext4_mb_initialize_context(struct ext4_allocation_context *ac,
ext4_get_group_no_and_offset(sb, goal, &group, &block);
/* set up allocation goals */
+ memset(ac, 0, sizeof(struct ext4_allocation_context));
ac->ac_b_ex.fe_logical = ar->logical;
- ac->ac_b_ex.fe_group = 0;
- ac->ac_b_ex.fe_start = 0;
- ac->ac_b_ex.fe_len = 0;
ac->ac_status = AC_STATUS_CONTINUE;
- ac->ac_groups_scanned = 0;
- ac->ac_ex_scanned = 0;
- ac->ac_found = 0;
ac->ac_sb = sb;
ac->ac_inode = ar->inode;
ac->ac_o_ex.fe_logical = ar->logical;
@@ -4245,15 +4240,7 @@ ext4_mb_initialize_context(struct ext4_allocation_context *ac,
ac->ac_g_ex.fe_group = group;
ac->ac_g_ex.fe_start = block;
ac->ac_g_ex.fe_len = len;
- ac->ac_f_ex.fe_len = 0;
ac->ac_flags = ar->flags;
- ac->ac_2order = 0;
- ac->ac_criteria = 0;
- ac->ac_pa = NULL;
- ac->ac_bitmap_page = NULL;
- ac->ac_buddy_page = NULL;
- ac->alloc_semp = NULL;
- ac->ac_lg = NULL;
/* we have to define context: we'll we work with a file or
* locality group. this is a policy, actually */
@@ -4521,10 +4508,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
}
ac = kmem_cache_alloc(ext4_ac_cachep, GFP_NOFS);
- if (ac) {
- ac->ac_sb = sb;
- ac->ac_inode = ar->inode;
- } else {
+ if (!ac) {
ar->len = 0;
*errp = -ENOMEM;
goto out1;