The "ibm,arch-vec-5-platform-support" property is a list of pairs of bytes representing the options and values supported by the platform firmware. At boot time, Linux scans this list and activates the available features it recognizes : Radix and XIVE.
A recent change modified the number of entries to loop on and 8 bytes, 4 pairs of { options, values } entries are always scanned. This is fine on KVM but not on PowerVM which can advertises less. As a consequence on this platform, Linux reads extra entries pointing to random data, interprets these as available features and tries to activate them, leading to a firmware crash in ibm,client-architecture-support.
Fix that by using the property length of "ibm,arch-vec-5-platform-support".
Cc: stable@vger.kernel.org # v4.20+ Fixes: ab91239942a9 ("powerpc/prom: Remove VLA in prom_check_platform_support()") Signed-off-by: Cédric Le Goater clg@kaod.org --- arch/powerpc/kernel/prom_init.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c index e9d4eb6144e1..ccf77b985c8f 100644 --- a/arch/powerpc/kernel/prom_init.c +++ b/arch/powerpc/kernel/prom_init.c @@ -1331,14 +1331,10 @@ static void __init prom_check_platform_support(void) if (prop_len > sizeof(vec)) prom_printf("WARNING: ibm,arch-vec-5-platform-support longer than expected (len: %d)\n", prop_len); - prom_getprop(prom.chosen, "ibm,arch-vec-5-platform-support", - &vec, sizeof(vec)); - for (i = 0; i < sizeof(vec); i += 2) { - prom_debug("%d: index = 0x%x val = 0x%x\n", i / 2 - , vec[i] - , vec[i + 1]); - prom_parse_platform_support(vec[i], vec[i + 1], - &supported); + prom_getprop(prom.chosen, "ibm,arch-vec-5-platform-support", &vec, sizeof(vec)); + for (i = 0; i < prop_len; i += 2) { + prom_debug("%d: index = 0x%x val = 0x%x\n", i / 2, vec[i], vec[i + 1]); + prom_parse_platform_support(vec[i], vec[i + 1], &supported); } }