[PATCH] rock.c: handle corrupted directories
The bug in rock.c is that it's totally trusting of the contents of the
directories. If the directory says there's a continuation 10000 bytes into
this 4k block then we cheerily poke around in memory we don't own and oops.
So change rock_continue() to apply various sanity checks, at least ensuring
that the offset+length remain within the bounds for the header part of a
struct rock_ridge directory entry.
Note that the kernel can still overindex the buffer due to the variable size
of the rock-ridge directory entries. We cannot check that in rock_continue()
unless we go parse the directory entry's signature and work out its size.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c
index 977dd70..9a81830 100644
--- a/fs/isofs/rock.c
+++ b/fs/isofs/rock.c
@@ -81,9 +81,22 @@
static int rock_continue(struct rock_state *rs)
{
int ret = 1;
+ int blocksize = 1 << rs->inode->i_blkbits;
+ const int min_de_size = offsetof(struct rock_ridge, u);
kfree(rs->buffer);
rs->buffer = NULL;
+
+ if ((unsigned)rs->cont_offset > blocksize - min_de_size ||
+ (unsigned)rs->cont_size > blocksize ||
+ (unsigned)(rs->cont_offset + rs->cont_size) > blocksize) {
+ printk(KERN_NOTICE "rock: corrupted directory entry. "
+ "extent=%d, offset=%d, size=%d\n",
+ rs->cont_extent, rs->cont_offset, rs->cont_size);
+ ret = -EIO;
+ goto out;
+ }
+
if (rs->cont_extent) {
struct buffer_head *bh;
