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authorRobin Holt <holt@sgi.com>2009-12-15 16:47:57 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-16 07:20:14 -0800
commit15b87d67ff3dc042bee42f991858d6b121b3b3ca (patch)
tree48e72a7ce8b4113b3dfcdcd31ca9bdce38ee3cd9 /drivers/misc
parentc2c9f115741453715d6b4da1cd2de65af8c7ad86 (diff)
x86: uv: xpc NULL deref when mesq becomes empty
Under heavy load conditions, our set of xpc messages may become exhausted. The code handles this correctly with the exception of the management code which hits a NULL pointer dereference. Signed-off-by: Robin Holt <holt@sgi.com> Cc: Jack Steiner <steiner@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/sgi-xp/xpc_uv.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
index bbf0e2ee6fd..19bd7b0ede9 100644
--- a/drivers/misc/sgi-xp/xpc_uv.c
+++ b/drivers/misc/sgi-xp/xpc_uv.c
@@ -949,11 +949,13 @@ xpc_get_fifo_entry_uv(struct xpc_fifo_head_uv *head)
head->first = first->next;
if (head->first == NULL)
head->last = NULL;
+
+ head->n_entries--;
+ BUG_ON(head->n_entries < 0);
+
+ first->next = NULL;
}
- head->n_entries--;
- BUG_ON(head->n_entries < 0);
spin_unlock_irqrestore(&head->lock, irq_flags);
- first->next = NULL;
return first;
}