[PATCH] [27/98] ARM: 6891/1: prevent heap corruption in OABI semtimedop

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>

commit 0f22072ab50cac7983f9660d33974b45184da4f9 upstream.

When CONFIG_OABI_COMPAT is set, the wrapper for semtimedop does not
bound the nsops argument.  A sufficiently large value will cause an
integer overflow in allocation size, followed by copying too much data
into the allocated buffer.  Fix this by restricting nsops to SEMOPM.
Untested.

Signed-off-by: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 arch/arm/kernel/sys_oabi-compat.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.35.y/arch/arm/kernel/sys_oabi-compat.c
===================================================================
--- linux-2.6.35.y.orig/arch/arm/kernel/sys_oabi-compat.c
+++ linux-2.6.35.y/arch/arm/kernel/sys_oabi-compat.c
@@ -311,7 +311,7 @@ asmlinkage long sys_oabi_semtimedop(int 
 	long err;
 	int i;
 
-	if (nsops < 1)
+	if (nsops < 1 || nsops > SEMOPM)
 		return -EINVAL;
 	sops = kmalloc(sizeof(*sops) * nsops, GFP_KERNEL);
 	if (!sops)
--
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