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x86: uv: xpc NULL deref when mesq becomes empty

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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>
This commit is contained in:
Robin Holt 2009-12-15 16:47:57 -08:00 • committed by Linus Torvalds
parent c2c9f11574
commit 15b87d67ff
1 changed files with 5 additions and 3 deletions
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8
drivers/misc/sgi-xp/xpc_uv.c
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@ -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;
}