From: Andrew Donnellan Date: Fri, 18 Mar 2016 06:36:33 +0000 (+1100) Subject: powerpc/rtas: Fix array overrun in ppc_rtas() syscall X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=a9862c7440f191439a51f77233f89f7e40efe02e;p=deliverable%2Flinux.git powerpc/rtas: Fix array overrun in ppc_rtas() syscall If ppc_rtas() is called with args.nargs == 16 and args.nret == 0, args.rets is set to point to &args.args[16], which is beyond the end of the args.args array. This results in a minor read overrun of the array when we check the first return code (which, per PAPR, is a required output of all RTAS calls) to see if there's been a hardware error. Change the nargs/nret check to ensure nargs is <= 15, allowing room for the status code. Users shouldn't be calling with nret == 0, but there's no real harm if they do, so we don't stop them. Signed-off-by: Andrew Donnellan Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 28736ff27fea..8da209fdf480 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -1070,7 +1070,7 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs) nret = be32_to_cpu(args.nret); token = be32_to_cpu(args.token); - if (nargs > ARRAY_SIZE(args.args) + if (nargs >= ARRAY_SIZE(args.args) || nret > ARRAY_SIZE(args.args) || nargs + nret > ARRAY_SIZE(args.args)) return -EINVAL;