This is a note to let you know that I've just added the patch titled powerpc/prom: Fix "ibm,arch-vec-5-platform-support" scan to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-prom-fix-ibm-arch-vec-5-platform-support-scan.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From ed5b00a05c2ae95b59adc3442f45944ec632e794 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= <clg@xxxxxxxx> Date: Fri, 22 Jan 2021 08:50:29 +0100 Subject: powerpc/prom: Fix "ibm,arch-vec-5-platform-support" scan MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Cédric Le Goater <clg@xxxxxxxx> commit ed5b00a05c2ae95b59adc3442f45944ec632e794 upstream. 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". Fixes: ab91239942a9 ("powerpc/prom: Remove VLA in prom_check_platform_support()") Cc: stable@xxxxxxxxxxxxxxx # v4.20+ Signed-off-by: Cédric Le Goater <clg@xxxxxxxx> Reviewed-by: Fabiano Rosas <farosas@xxxxxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210122075029.797013-1-clg@xxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/powerpc/kernel/prom_init.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) --- a/arch/powerpc/kernel/prom_init.c +++ b/arch/powerpc/kernel/prom_init.c @@ -1330,14 +1330,10 @@ static void __init prom_check_platform_s 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); } } Patches currently in stable-queue which might be from clg@xxxxxxxx are queue-5.10/kvm-ppc-make-the-vmx-instruction-emulation-routines-.patch queue-5.10/powerpc-prom-fix-ibm-arch-vec-5-platform-support-scan.patch