[PATCH] Possible fix for 2.6.24 xfs_file_readdir crash

David Chinner
2008-02-05T05:24:37Z

Sven, Tomas, Andrea:

Can you try the patch attached below to see if it fixes the
xfs_file_readdir() oops you are seeing and let me know if it fixes
the problem?

It looks like we're deferencing a pointer beyond the end of a buffer
if the buffer is filled exactly. This bug does not crash ia64 (even
with memory poisoning enabled), which is why the targeted corner
case testing I did a while back did not pick this up when fixing a
similar bug a month ago.

Cheers,

Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group

---
Fix yet another corner case oops in xfs_file_readdir().

Signed-off-by: Dave Chinner <dgc@sgi.com>
---
fs/xfs/linux-2.6/xfs_file.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_file.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_file.c 2008-01-16 16:24:01.000000000 +1100
+++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_file.c 2008-02-05 15:13:17.153110696 +1100
@@ -351,8 +351,8 @@ xfs_file_readdir(

size = buf.used;
de = (struct hack_dirent *)buf.dirent;
- curr_offset = de->offset /* & 0x7fffffff */;
while (size > 0) {
+ curr_offset = de->offset /* & 0x7fffffff */;
if (filldir(dirent, de->name, de->namlen,
curr_offset & 0x7fffffff,
de->ino, de->d_type)) {
@@ -363,7 +363,6 @@ xfs_file_readdir(
sizeof(u64));
size -= reclen;
de = (struct hack_dirent *)((char *)de + reclen);
- curr_offset = de->offset /* & 0x7fffffff */;
}
}