From: Greg KH <[email protected]> 3.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andreas Herrmann <[email protected]> commit 36bf50d7697be18c6bfd0401e037df10bff1e573 upstream. This issue was recently observed on an AMD C-50 CPU where a patch of maximum size was applied. Commit be62adb49294 ("x86, microcode, AMD: Simplify ucode verification") added current_size in get_matching_microcode(). This is calculated as size of the ucode patch + 8 (ie. size of the header). Later this is compared against the maximum possible ucode patch size for a CPU family. And of course this fails if the patch has already maximum size. Signed-off-by: Andreas Herrmann <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: H. Peter Anvin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/microcode_amd.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/microcode_amd.c +++ b/arch/x86/kernel/microcode_amd.c @@ -143,11 +143,12 @@ static int get_matching_microcode(int cp unsigned int *current_size) { struct microcode_header_amd *mc_hdr; - unsigned int actual_size; + unsigned int actual_size, patch_size; u16 equiv_cpu_id; /* size of the current patch we're staring at */ - *current_size = *(u32 *)(ucode_ptr + 4) + SECTION_HDR_SIZE; + patch_size = *(u32 *)(ucode_ptr + 4); + *current_size = patch_size + SECTION_HDR_SIZE; equiv_cpu_id = find_equiv_id(); if (!equiv_cpu_id) @@ -174,7 +175,7 @@ static int get_matching_microcode(int cp /* * now that the header looks sane, verify its size */ - actual_size = verify_ucode_size(cpu, *current_size, leftover_size); + actual_size = verify_ucode_size(cpu, patch_size, leftover_size); if (!actual_size) return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
