0119-disk-lvm-Don-t-blast-past-the-end-of-the-circular-me.patch 1.5 KB

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  1. From 27a79bf38e6d050e497eb96a3fdddce43af25577 Mon Sep 17 00:00:00 2001
  2. From: Daniel Axtens <dja@axtens.net>
  3. Date: Thu, 21 Jan 2021 18:19:51 +1100
  4. Subject: [PATCH] disk/lvm: Don't blast past the end of the circular metadata
  5. buffer
  6. This catches at least some OOB reads, and it's possible I suppose that
  7. if 2 * mda_size is less than GRUB_LVM_MDA_HEADER_SIZE it might catch some
  8. OOB writes too (although that hasn't showed up as a crash in fuzzing yet).
  9. It's a bit ugly and I'd appreciate better suggestions.
  10. Signed-off-by: Daniel Axtens <dja@axtens.net>
  11. Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
  12. Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
  13. ---
  14. grub-core/disk/lvm.c | 10 ++++++++++
  15. 1 file changed, 10 insertions(+)
  16. diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c
  17. index 8136122..36da575 100644
  18. --- a/grub-core/disk/lvm.c
  19. +++ b/grub-core/disk/lvm.c
  20. @@ -214,6 +214,16 @@ grub_lvm_detect (grub_disk_t disk,
  21. if (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) >
  22. grub_le_to_cpu64 (mdah->size))
  23. {
  24. + if (2 * mda_size < GRUB_LVM_MDA_HEADER_SIZE ||
  25. + (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) -
  26. + grub_le_to_cpu64 (mdah->size) > mda_size - GRUB_LVM_MDA_HEADER_SIZE))
  27. + {
  28. +#ifdef GRUB_UTIL
  29. + grub_util_info ("cannot copy metadata wrap in circular buffer");
  30. +#endif
  31. + goto fail2;
  32. + }
  33. +
  34. /* Metadata is circular. Copy the wrap in place. */
  35. grub_memcpy (metadatabuf + mda_size,
  36. metadatabuf + GRUB_LVM_MDA_HEADER_SIZE,
  37. --
  38. 2.14.2