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| author | Jim Meyering <jim@meyering.net> | 2012-10-16 17:43:49 +0200 |
|---|---|---|
| committer | Jim Meyering <jim@meyering.net> | 2012-10-17 18:17:56 +0200 |
| commit | 64aef5fb9afecc023a6e719da161dbbf450908b8 (patch) | |
| tree | a592f63d1dd77c6f946eb594a4828468f100db58 /src/extent-scan.c | |
| parent | c528f13136c8b3ed89d5d59bdc04f99872e10fa7 (diff) | |
| download | coreutils-64aef5fb9afecc023a6e719da161dbbf450908b8.tar.xz | |
cp: avoid data-corrupting free-memory-read
* src/extent-scan.c (extent_scan_read): Reset our last_ei
pointer whenever the parent buffer might have just been freed.
* tests/cp/fiemap-extent-FMR.sh: New test.
* tests/local.mk (all_tests): Add it.
* NEWS (Bug fixes): Mention it.
Reported by Mike Gerth in http://bugs.gnu.org/12656, and with
help from Alan Curry. Bug introduced in commit v8.10-60-g18f5a85.
Diffstat (limited to 'src/extent-scan.c')
| -rw-r--r-- | src/extent-scan.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/src/extent-scan.c b/src/extent-scan.c index 0c25c5705..f96229855 100644 --- a/src/extent-scan.c +++ b/src/extent-scan.c @@ -89,7 +89,7 @@ extern bool extent_scan_read (struct extent_scan *scan) { unsigned int si = 0; - struct extent_info *last_ei IF_LINT ( = scan->ext_info); + struct extent_info *last_ei = scan->ext_info; while (true) { @@ -127,8 +127,14 @@ extent_scan_read (struct extent_scan *scan) assert (scan->ei_count <= SIZE_MAX - fiemap->fm_mapped_extents); scan->ei_count += fiemap->fm_mapped_extents; - scan->ext_info = xnrealloc (scan->ext_info, scan->ei_count, - sizeof (struct extent_info)); + { + /* last_ei points into a buffer that may be freed via xnrealloc. + Record its offset and adjust after allocation. */ + size_t prev_idx = last_ei - scan->ext_info; + scan->ext_info = xnrealloc (scan->ext_info, scan->ei_count, + sizeof (struct extent_info)); + last_ei = scan->ext_info + prev_idx; + } unsigned int i = 0; for (i = 0; i < fiemap->fm_mapped_extents; i++) |