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authorCarlos Maiolino <cmaiolino@redhat.com>2012-09-17 23:39:12 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-09-17 23:39:12 -0400
commit90b0a97323f42ead278bbccbdf0e123db2add400 (patch)
tree2b99c6b0f848af4392e8be794d3c56338d6ced85 /fs/ext4/namei.c
parentbc0b75f77a944b482293972eb8fd5c88c576eb46 (diff)
ext4: fix possible non-initialized variable in htree_dirblock_to_tree()
htree_dirblock_to_tree() declares a non-initialized 'err' variable, which is passed as a reference to another functions expecting them to set this variable with their error codes. It's passed to ext4_bread(), which then passes it to ext4_getblk(). If ext4_map_blocks() returns 0 due to a lookup failure, leaving the ext4_getblk() buffer_head uninitialized, it will make ext4_getblk() return to ext4_bread() without initialize the 'err' variable, and ext4_bread() will return to htree_dirblock_to_tree() with this variable still uninitialized. htree_dirblock_to_tree() will pass this variable with garbage back to ext4_htree_fill_tree(), which expects a number of directory entries added to the rb-tree. which, in case, might return a fake non-zero value due the garbage left in the 'err' variable, leading the kernel to an Oops in ext4_dx_readdir(), once this is expecting a filled rb-tree node, when in turn it will have a NULL-ed one, causing an invalid page request when trying to get a fname struct from this NULL-ed rb-tree node in this line: fname = rb_entry(info->curr_node, struct fname, rb_hash); The patch itself initializes the err variable in htree_dirblock_to_tree() to avoid usage mistakes by the called functions, and also fix ext4_getblk() to return a initialized 'err' variable when ext4_map_blocks() fails a lookup. Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/namei.c')
-rw-r--r--fs/ext4/namei.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 7450ff01c3c..37c03b32e19 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -846,7 +846,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
{
struct buffer_head *bh;
struct ext4_dir_entry_2 *de, *top;
- int err, count = 0;
+ int err = 0, count = 0;
dxtrace(printk(KERN_INFO "In htree dirblock_to_tree: block %lu\n",
(unsigned long)block));