1*4882a593SmuzhiyunFrom ab51d587bb9b229b1fade1afd02e1574c1ba5c76 Mon Sep 17 00:00:00 2001 2*4882a593SmuzhiyunFrom: Lukas Czerner <lczerner@redhat.com> 3*4882a593SmuzhiyunDate: Thu, 21 Apr 2022 19:31:48 +0200 4*4882a593SmuzhiyunSubject: libext2fs: add sanity check to extent manipulation 5*4882a593Smuzhiyun 6*4882a593SmuzhiyunIt is possible to have a corrupted extent tree in such a way that a leaf 7*4882a593Smuzhiyunnode contains zero extents in it. Currently if that happens and we try 8*4882a593Smuzhiyunto traverse the tree we can end up accessing wrong data, or possibly 9*4882a593Smuzhiyuneven uninitialized memory. Make sure we don't do that. 10*4882a593Smuzhiyun 11*4882a593SmuzhiyunAdditionally make sure that we have a sane number of bytes passed to 12*4882a593Smuzhiyunmemmove() in ext2fs_extent_delete(). 13*4882a593Smuzhiyun 14*4882a593SmuzhiyunNote that e2fsck is currently unable to spot and fix such corruption in 15*4882a593Smuzhiyunpass1. 16*4882a593Smuzhiyun 17*4882a593SmuzhiyunSigned-off-by: Lukas Czerner <lczerner@redhat.com> 18*4882a593SmuzhiyunReported-by: Nils Bars <nils_bars@t-online.de> 19*4882a593SmuzhiyunAddresses: https://bugzilla.redhat.com/show_bug.cgi?id=2068113 20*4882a593SmuzhiyunAddresses: CVE-2022-1304 21*4882a593SmuzhiyunAddresses-Debian-Bug: #1010263 22*4882a593SmuzhiyunSigned-off-by: Theodore Ts'o <tytso@mit.edu> 23*4882a593Smuzhiyun 24*4882a593Smuzhiyun[Retrieved from: 25*4882a593Smuzhiyunhttps://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/commit/?h=maint&id=ab51d587bb9b229b1fade1afd02e1574c1ba5c76] 26*4882a593SmuzhiyunSigned-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com> 27*4882a593Smuzhiyun--- 28*4882a593Smuzhiyun lib/ext2fs/extent.c | 8 ++++++++ 29*4882a593Smuzhiyun 1 file changed, 8 insertions(+) 30*4882a593Smuzhiyun 31*4882a593Smuzhiyundiff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c 32*4882a593Smuzhiyunindex b324c7b0..1a206a16 100644 33*4882a593Smuzhiyun--- a/lib/ext2fs/extent.c 34*4882a593Smuzhiyun+++ b/lib/ext2fs/extent.c 35*4882a593Smuzhiyun@@ -495,6 +495,10 @@ retry: 36*4882a593Smuzhiyun ext2fs_le16_to_cpu(eh->eh_entries); 37*4882a593Smuzhiyun newpath->max_entries = ext2fs_le16_to_cpu(eh->eh_max); 38*4882a593Smuzhiyun 39*4882a593Smuzhiyun+ /* Make sure there is at least one extent present */ 40*4882a593Smuzhiyun+ if (newpath->left <= 0) 41*4882a593Smuzhiyun+ return EXT2_ET_EXTENT_NO_DOWN; 42*4882a593Smuzhiyun+ 43*4882a593Smuzhiyun if (path->left > 0) { 44*4882a593Smuzhiyun ix++; 45*4882a593Smuzhiyun newpath->end_blk = ext2fs_le32_to_cpu(ix->ei_block); 46*4882a593Smuzhiyun@@ -1630,6 +1634,10 @@ errcode_t ext2fs_extent_delete(ext2_extent_handle_t handle, int flags) 47*4882a593Smuzhiyun 48*4882a593Smuzhiyun cp = path->curr; 49*4882a593Smuzhiyun 50*4882a593Smuzhiyun+ /* Sanity check before memmove() */ 51*4882a593Smuzhiyun+ if (path->left < 0) 52*4882a593Smuzhiyun+ return EXT2_ET_EXTENT_LEAF_BAD; 53*4882a593Smuzhiyun+ 54*4882a593Smuzhiyun if (path->left) { 55*4882a593Smuzhiyun memmove(cp, cp + sizeof(struct ext3_extent_idx), 56*4882a593Smuzhiyun path->left * sizeof(struct ext3_extent_idx)); 57*4882a593Smuzhiyun-- 58*4882a593Smuzhiyuncgit 59*4882a593Smuzhiyun 60