+ x86-uv-xpc-null-deref-when-mesq-becomes-empty.patch added to -mm tree

+ x86-uv-xpc-null-deref-when-mesq-becomes-empty.patch added to -mm tree

[akpm]

The patch titled
     x86: uv: xpc NULL deref when mesq becomes empty
has been added to the -mm tree.  Its filename is
     x86-uv-xpc-null-deref-when-mesq-becomes-empty.patch

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------------------------------------------------------
Subject: x86: uv: xpc NULL deref when mesq becomes empty
From: Robin Holt <holt@sgi.com>

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.

To: Andrew Morton <akpm@linux-foundation.org>
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>
---

 drivers/misc/sgi-xp/xpc_uv.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff -puN drivers/misc/sgi-xp/xpc_uv.c~x86-uv-xpc-null-deref-when-mesq-becomes-empty drivers/misc/sgi-xp/xpc_uv.c
--- a/drivers/misc/sgi-xp/xpc_uv.c~x86-uv-xpc-null-deref-when-mesq-becomes-empty
+++ a/drivers/misc/sgi-xp/xpc_uv.c
@@ -949,11 +949,13 @@ xpc_get_fifo_entry_uv(struct xpc_fifo_he
 		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;
 }
 
_

Patches currently in -mm which might be from holt@sgi.com are

x86-uv-introduce-a-means-to-translate-from-gpa-socket_paddr.patch
x86-uv-xpc-needs-to-provide-an-abstraction-for-uv_gpa.patch
x86-uv-introduce-uv_gpa_is_mmr.patch
x86-uv-implement-a-gru_read_gpa-kernel-function.patch
x86-uv-update-xpc-to-handle-updated-bios-interface.patch
x86-uv-xpc-null-deref-when-mesq-becomes-empty.patch
x86-uv-xpc_make_first_contact-hang-due-to-not-accepting-active-state.patch
x86-uv-xpc-receive-message-reuse-triggers-invalid-bug_on.patch