Geert Uytterhoeven wrote:
On Fri, 17 Oct 2008, Phillip Lougher wrote:
--- /dev/null
+++ b/fs/squashfs/namei.c
+static int get_dir_index_using_name(struct super_block *s,
+ long long *next_block, unsigned int *next_offset,
+ long long index_start, unsigned int index_offset,
+ int i_count, const char *name, int len)
+{
+ struct squashfs_sb_info *msblk = s->s_fs_info;
+ int i, size, length = 0;
+ struct squashfs_dir_index *index;
+ char *str;
+
+ TRACE("Entered get_dir_index_using_name, i_count %d\n", i_count);
+
+ str = kmalloc(sizeof(*index) + (SQUASHFS_NAME_LEN + 1) * 2, GFP_KERNEL);
+ if (str == NULL) {
+ ERROR("Failed to allocate squashfs_dir_index\n");
+ goto out;
+ }
+
+ index = (struct squashfs_dir_index *) (str + SQUASHFS_NAME_LEN + 1);
As str has been returned by kmalloc(), and SQUASHFS_NAME_LEN is equal to 256,
`str + SQUASHFS_NAME_LEN + 1` is an odd address.
[..]
+ size = le32_to_cpu(index->size) + 1;
^^^^^^^^^^^
[.]
Hence accessing multi-byte fields in struct squashfs_dir_index causes unaligned
accesses, which are emulated on some architectures (e.g. on MIPS).
Use get_unaligned_le32() for unaligned accesses.
How about aligning it properly in the first place instead?
Three ways:
1) reordering index and str here, so that index comes first,
str next.
2) using another constant instead of +1
3) using separate allocations for separate objects.
/mjt
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