limit minixfs printks on corrupted dir i_size

This attempts to address CVE-2006-6058
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-6058

first reported at http://projects.info-pull.com/mokb/MOKB-17-11-2006.html

Essentially a corrupted minix dir inode reporting a very large
i_size will loop for a very long time in minix_readdir, minix_find_entry,
etc, because on EIO they just move on to try the next page.  This is
under the BKL, printk-storming as well.  This can lock up the machine
for a very long time.  Simply ratelimiting the printks gets things back
under control.  Make the message a bit more informative while we're here.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Bodo Eggert <7eggert@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/minix/itree_v1.c b/fs/minix/itree_v1.c
index 1a5f3bf0bcec..82d6554b02fe 100644
--- a/fs/minix/itree_v1.c
+++ b/fs/minix/itree_v1.c
@@ -23,11 +23,16 @@ static inline block_t *i_data(struct inode *inode)
 static int block_to_path(struct inode * inode, long block, int offsets[DEPTH])
 {
         int n = 0;
+        char b[BDEVNAME_SIZE];
 
         if (block < 0) {
-                printk("minix_bmap: block<0\n");
+                printk("MINIX-fs: block_to_path: block %ld < 0 on dev %s\n",
+                        block, bdevname(inode->i_sb->s_bdev, b));
         } else if (block >= (minix_sb(inode->i_sb)->s_max_size/BLOCK_SIZE)) {
-                printk("minix_bmap: block>big\n");
+                if (printk_ratelimit())
+                        printk("MINIX-fs: block_to_path: "
+                               "block %ld too big on dev %s\n",
+                                block, bdevname(inode->i_sb->s_bdev, b));
         } else if (block < 7) {
                 offsets[n++] = block;
         } else if ((block -= 7) < 512) {