From f584bb6df7a25425d1045ebd3310b8ce00cec0e4 Mon Sep 17 00:00:00 2001 From: Darren Stevens Date: Mon, 23 Jan 2017 19:42:54 +0000 Subject: [PATCH] powerpc: Add missing error check to prom_find_boot_cpu() commit af2b7fa17eb92e52b65f96604448ff7a2a89ee99 upstream. prom_init.c calls 'instance-to-package' twice, but the return is not checked during prom_find_boot_cpu(). The result is then passed to prom_getprop(), which could be PROM_ERROR. Add a return check to prevent this. This was found on a pasemi system, where CFE doesn't have a working 'instance-to package' prom call. Before Commit 5c0484e25ec0 ('powerpc: Endian safe trampoline') the area around addr 0 was mostly 0's and this doesn't cause a problem. Once the macro 'FIXUP_ENDIAN' has been added to head_64.S, the low memory area now has non-zero values, which cause the prom_getprop() call to hang. mpe: Also confirmed that under SLOF if 'instance-to-package' did fail with PROM_ERROR we would crash in SLOF. So the bug is not specific to CFE, it's just that other open firmwares don't trigger it because they have a working 'instance-to-package'. Fixes: 5c0484e25ec0 ("powerpc: Endian safe trampoline") Signed-off-by: Darren Stevens Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/prom_init.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c index 7b89e7b..3139533 100644 --- a/arch/powerpc/kernel/prom_init.c +++ b/arch/powerpc/kernel/prom_init.c @@ -2664,6 +2664,9 @@ static void __init prom_find_boot_cpu(void) cpu_pkg = call_prom("instance-to-package", 1, 1, prom_cpu); + if (!PHANDLE_VALID(cpu_pkg)) + return; + prom_getprop(cpu_pkg, "reg", &rval, sizeof(rval)); prom.cpu = be32_to_cpu(rval); -- 2.7.4