0110-fs-jfs-Catch-infinite-recursion.patch 1.6 KB

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  1. From 223120dd83745126cb232a0248c9a8901d7e350d Mon Sep 17 00:00:00 2001
  2. From: Daniel Axtens <dja@axtens.net>
  3. Date: Mon, 18 Jan 2021 15:47:24 +1100
  4. Subject: [PATCH] fs/jfs: Catch infinite recursion
  5. It's possible with a fuzzed filesystem for JFS to keep getblk()-ing
  6. the same data over and over again, leading to stack exhaustion.
  7. Check if we'd be calling the function with exactly the same data as
  8. was passed in, and if so abort.
  9. I'm not sure what the performance impact of this is and am open to
  10. better ideas.
  11. Signed-off-by: Daniel Axtens <dja@axtens.net>
  12. Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
  13. Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
  14. ---
  15. grub-core/fs/jfs.c | 11 ++++++++++-
  16. 1 file changed, 10 insertions(+), 1 deletion(-)
  17. diff --git a/grub-core/fs/jfs.c b/grub-core/fs/jfs.c
  18. index 804c42d..6f7c439 100644
  19. --- a/grub-core/fs/jfs.c
  20. +++ b/grub-core/fs/jfs.c
  21. @@ -304,7 +304,16 @@ getblk (struct grub_jfs_treehead *treehead,
  22. << (grub_le_to_cpu16 (data->sblock.log2_blksz)
  23. - GRUB_DISK_SECTOR_BITS), 0,
  24. sizeof (*tree), (char *) tree))
  25. - ret = getblk (&tree->treehead, &tree->extents[0], 254, data, blk);
  26. + {
  27. + if (grub_memcmp (&tree->treehead, treehead, sizeof (struct grub_jfs_treehead)) ||
  28. + grub_memcmp (&tree->extents, extents, 254 * sizeof (struct grub_jfs_tree_extent)))
  29. + ret = getblk (&tree->treehead, &tree->extents[0], 254, data, blk);
  30. + else
  31. + {
  32. + grub_error (GRUB_ERR_BAD_FS, "jfs: infinite recursion detected");
  33. + ret = -1;
  34. + }
  35. + }
  36. grub_free (tree);
  37. return ret;
  38. }
  39. --
  40. 2.14.2