From: Daniel Axtens Date: Thu, 21 Jan 2021 07:19:51 +0000 (+1100) Subject: disk/lvm: Don't blast past the end of the circular metadata buffer X-Git-Tag: grub-2.06-rc1~56 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27a79bf38e6d050e497eb96a3fdddce43af25577;p=thirdparty%2Fgrub.git disk/lvm: Don't blast past the end of the circular metadata buffer This catches at least some OOB reads, and it's possible I suppose that if 2 * mda_size is less than GRUB_LVM_MDA_HEADER_SIZE it might catch some OOB writes too (although that hasn't showed up as a crash in fuzzing yet). It's a bit ugly and I'd appreciate better suggestions. Signed-off-by: Daniel Axtens Reviewed-by: Daniel Kiper --- diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c index 6988fe492..b70d7d79f 100644 --- a/grub-core/disk/lvm.c +++ b/grub-core/disk/lvm.c @@ -251,6 +251,16 @@ grub_lvm_detect (grub_disk_t disk, if (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) > grub_le_to_cpu64 (mdah->size)) { + if (2 * mda_size < GRUB_LVM_MDA_HEADER_SIZE || + (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) - + grub_le_to_cpu64 (mdah->size) > mda_size - GRUB_LVM_MDA_HEADER_SIZE)) + { +#ifdef GRUB_UTIL + grub_util_info ("cannot copy metadata wrap in circular buffer"); +#endif + goto fail2; + } + /* Metadata is circular. Copy the wrap in place. */ grub_memcpy (metadatabuf + mda_size, metadatabuf + GRUB_LVM_MDA_HEADER_SIZE,