| From: Wang Shilong <wshilong@ddn.com> |
| Date: Mon, 30 Dec 2019 19:52:39 -0500 |
| Subject: e2fsck: fix use after free in calculate_tree() |
| |
| The problem is alloc_blocks() will call get_next_block() which might |
| reallocate outdir->buf, and memory address could be changed after |
| this. To fix this, pointers that point into outdir->buf, such as |
| int_limit and root need to be recaulated based on the new starting |
| address of outdir->buf. |
| |
| [ Changed to correctly recalculate int_limit, and to optimize how we |
| reallocate outdir->buf. -TYT ] |
| |
| Addresses-Debian-Bug: 948517 |
| Signed-off-by: Wang Shilong <wshilong@ddn.com> |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| (cherry picked from commit 101e73e99ccafa0403fcb27dd7413033b587ca01) |
| |
| Signed-off-by: Anuj Mittal <anuj.mittal@intel.com> |
| Upstream-Status: Backport [https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/commit/?id=101e73e99ccafa0403fcb27dd7413033b587ca01] |
| --- |
| e2fsck/rehash.c | 17 ++++++++++++++++- |
| 1 file changed, 16 insertions(+), 1 deletion(-) |
| |
| diff --git a/e2fsck/rehash.c b/e2fsck/rehash.c |
| index 0a5888a9..2574e151 100644 |
| --- a/e2fsck/rehash.c |
| +++ b/e2fsck/rehash.c |
| @@ -295,7 +295,11 @@ static errcode_t get_next_block(ext2_filsys fs, struct out_dir *outdir, |
| errcode_t retval; |
| |
| if (outdir->num >= outdir->max) { |
| - retval = alloc_size_dir(fs, outdir, outdir->max + 50); |
| + int increment = outdir->max / 10; |
| + |
| + if (increment < 50) |
| + increment = 50; |
| + retval = alloc_size_dir(fs, outdir, outdir->max + increment); |
| if (retval) |
| return retval; |
| } |
| @@ -637,6 +641,9 @@ static int alloc_blocks(ext2_filsys fs, |
| if (retval) |
| return retval; |
| |
| + /* outdir->buf might be reallocated */ |
| + *prev_ent = (struct ext2_dx_entry *) (outdir->buf + *prev_offset); |
| + |
| *next_ent = set_int_node(fs, block_start); |
| *limit = (struct ext2_dx_countlimit *)(*next_ent); |
| if (next_offset) |
| @@ -726,6 +733,9 @@ static errcode_t calculate_tree(ext2_filsys fs, |
| return retval; |
| } |
| if (c3 == 0) { |
| + int delta1 = (char *)int_limit - outdir->buf; |
| + int delta2 = (char *)root - outdir->buf; |
| + |
| retval = alloc_blocks(fs, &limit, &int_ent, |
| &dx_ent, &int_offset, |
| NULL, outdir, i, &c2, |
| @@ -733,6 +743,11 @@ static errcode_t calculate_tree(ext2_filsys fs, |
| if (retval) |
| return retval; |
| |
| + /* outdir->buf might be reallocated */ |
| + int_limit = (struct ext2_dx_countlimit *) |
| + (outdir->buf + delta1); |
| + root = (struct ext2_dx_entry *) |
| + (outdir->buf + delta2); |
| } |
| dx_ent->block = ext2fs_cpu_to_le32(i); |
| if (c3 != limit->limit) |
| -- |
| 2.24.1 |
| |