mm: slab: Verify the nodeid passed to ____cache_alloc_node

PATCH Aaron Tomlin 3 participants 3 messages Feb 25, 2013 1 message not in the archive Memory management

lore

Share & tools

lore

Aaron Tomlin

author

2013-02-25 17:18 UTC #1 lore raw

In reply to a message not in the archive

Hi,

This patch is in response to bz#42967 [1]. Using VM_BUG_ON instead of a generic BUG_ON so it's used only when CONFIG_DEBUG_VM is set, given that ____cache_alloc_node() is a hot code path.

Cheers,
Aaron

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=42967

---8<---
mm: slab: Verify the nodeid passed to ____cache_alloc_node

If the nodeid is > num_online_nodes() this can cause an Oops and a panic(). The purpose of this patch is to assert if this condition is true to aid debugging efforts rather than some random NULL pointer dereference or page fault.

Signed-off-by Aaron Tomlin <[email protected]>

 slab.c |    1 +
 1 file changed, 1 insertion(+)

mm/slab.c +1 -0

index e7667a3..735e8bd 100644
@@ -3412,6 +3412,7 @@ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
 	void *obj;
 	int x;
 
+	VM_BUG_ON(nodeid > num_online_nodes());
 	l3 = cachep->nodelists[nodeid];
 	BUG_ON(!l3);

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Rik van Riel

Reviewed-by

2013-02-25 17:45 UTC #2 lore raw

Quoted 8 lines · Aaron Tomlin

mm: slab: Verify the nodeid passed to ____cache_alloc_node
If the nodeid is > num_online_nodes() this can cause an Oops and a panic(). The purpose of this patch is to assert if this condition is true to aid debugging efforts rather than some random NULL pointer dereference or page fault.
Signed-off-by Aaron Tomlin <[email protected]>

Reviewed-by Rik van Riel <[email protected]>

Signature · 7 lines

All rights reversed

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to [email protected].  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Christoph Lameter

2013-02-25 19:27 UTC #3 lore raw

Quoted 4 lines · Rik van Riel

Quoted 2 lines · Aaron Tomlin
mm: slab: Verify the nodeid passed to ____cache_alloc_node

Quoted 8 lines

Quoted 6 lines
If the nodeid is > num_online_nodes() this can cause an Oops and a panic(). The purpose of this patch is to assert if this condition is true to aid debugging efforts rather than some random NULL pointer dereference or page fault.
Signed-off-by Aaron Tomlin <[email protected]>
Reviewed-by Rik van Riel <[email protected]>

It may be helpful to cc the slab maintainers...