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| author | Carlos Maiolino <cmaiolino@redhat.com> | 2012-09-17 23:39:12 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2012-09-17 23:39:12 -0400 |
| commit | 90b0a97323f42ead278bbccbdf0e123db2add400 (patch) | |
| tree | 2b99c6b0f848af4392e8be794d3c56338d6ced85 /fs/ext4/inode.c | |
| parent | bc0b75f77a944b482293972eb8fd5c88c576eb46 (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/inode.c')
| -rw-r--r-- | fs/ext4/inode.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index b4effbda7a9..ca76b5ed6c9 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -732,11 +732,13 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode, err = ext4_map_blocks(handle, inode, &map, create ? EXT4_GET_BLOCKS_CREATE : 0); + /* ensure we send some value back into *errp */ + *errp = 0; + if (err < 0) *errp = err; if (err <= 0) return NULL; - *errp = 0; bh = sb_getblk(inode->i_sb, map.m_pblk); if (!bh) { |