1*4882a593SmuzhiyunFrom 27a79bf38e6d050e497eb96a3fdddce43af25577 Mon Sep 17 00:00:00 2001 2*4882a593SmuzhiyunFrom: Daniel Axtens <dja@axtens.net> 3*4882a593SmuzhiyunDate: Thu, 21 Jan 2021 18:19:51 +1100 4*4882a593SmuzhiyunSubject: [PATCH] disk/lvm: Don't blast past the end of the circular metadata 5*4882a593Smuzhiyun buffer 6*4882a593Smuzhiyun 7*4882a593SmuzhiyunThis catches at least some OOB reads, and it's possible I suppose that 8*4882a593Smuzhiyunif 2 * mda_size is less than GRUB_LVM_MDA_HEADER_SIZE it might catch some 9*4882a593SmuzhiyunOOB writes too (although that hasn't showed up as a crash in fuzzing yet). 10*4882a593Smuzhiyun 11*4882a593SmuzhiyunIt's a bit ugly and I'd appreciate better suggestions. 12*4882a593Smuzhiyun 13*4882a593SmuzhiyunSigned-off-by: Daniel Axtens <dja@axtens.net> 14*4882a593SmuzhiyunReviewed-by: Daniel Kiper <daniel.kiper@oracle.com> 15*4882a593SmuzhiyunSigned-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com> 16*4882a593Smuzhiyun--- 17*4882a593Smuzhiyun grub-core/disk/lvm.c | 10 ++++++++++ 18*4882a593Smuzhiyun 1 file changed, 10 insertions(+) 19*4882a593Smuzhiyun 20*4882a593Smuzhiyundiff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c 21*4882a593Smuzhiyunindex 8136122..36da575 100644 22*4882a593Smuzhiyun--- a/grub-core/disk/lvm.c 23*4882a593Smuzhiyun+++ b/grub-core/disk/lvm.c 24*4882a593Smuzhiyun@@ -214,6 +214,16 @@ grub_lvm_detect (grub_disk_t disk, 25*4882a593Smuzhiyun if (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) > 26*4882a593Smuzhiyun grub_le_to_cpu64 (mdah->size)) 27*4882a593Smuzhiyun { 28*4882a593Smuzhiyun+ if (2 * mda_size < GRUB_LVM_MDA_HEADER_SIZE || 29*4882a593Smuzhiyun+ (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) - 30*4882a593Smuzhiyun+ grub_le_to_cpu64 (mdah->size) > mda_size - GRUB_LVM_MDA_HEADER_SIZE)) 31*4882a593Smuzhiyun+ { 32*4882a593Smuzhiyun+#ifdef GRUB_UTIL 33*4882a593Smuzhiyun+ grub_util_info ("cannot copy metadata wrap in circular buffer"); 34*4882a593Smuzhiyun+#endif 35*4882a593Smuzhiyun+ goto fail2; 36*4882a593Smuzhiyun+ } 37*4882a593Smuzhiyun+ 38*4882a593Smuzhiyun /* Metadata is circular. Copy the wrap in place. */ 39*4882a593Smuzhiyun grub_memcpy (metadatabuf + mda_size, 40*4882a593Smuzhiyun metadatabuf + GRUB_LVM_MDA_HEADER_SIZE, 41*4882a593Smuzhiyun-- 42*4882a593Smuzhiyun2.14.2 43*4882a593Smuzhiyun 44