[PATCH v3 13/22] write_untracked_extension: use FLEX_ALLOC helper
From: Jeff King <hidden>
Date: 2016-06-15 23:08:22
Subsystem:
the rest · Maintainer:
Linus Torvalds
We perform unchecked additions when computing the size of a "struct ondisk_untracked_cache". This is unlikely to have an integer overflow in practice, but we'd like to avoid this dangerous pattern to make further audits easier. Note that there's one subtlety here, though. We protect ourselves against a NULL exclude_per_dir entry in our source, and avoid calling strlen() on it, keeping "len" at 0. But later, we unconditionally memcpy "len + 1" bytes to get the trailing NUL byte. If we did have a NULL exclude_per_dir, we would read from bogus memory. As it turns out, though, we always create this field pointing to a string literal, so there's no bug. We can just get rid of the pointless extra conditional. Signed-off-by: Jeff King <redacted> --- dir.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/dir.c b/dir.c
index 2c91541..a4a9d9f 100644
--- a/dir.c
+++ b/dir.c@@ -2360,16 +2360,15 @@ void write_untracked_extension(struct strbuf *out, struct untracked_cache *untra struct ondisk_untracked_cache *ouc; struct write_data wd; unsigned char varbuf[16]; - int len = 0, varint_len; - if (untracked->exclude_per_dir) - len = strlen(untracked->exclude_per_dir); - ouc = xmalloc(sizeof(*ouc) + len + 1); + int varint_len; + size_t len = strlen(untracked->exclude_per_dir); + + FLEX_ALLOC_MEM(ouc, exclude_per_dir, untracked->exclude_per_dir, len); stat_data_to_disk(&ouc->info_exclude_stat, &untracked->ss_info_exclude.stat); stat_data_to_disk(&ouc->excludes_file_stat, &untracked->ss_excludes_file.stat); hashcpy(ouc->info_exclude_sha1, untracked->ss_info_exclude.sha1); hashcpy(ouc->excludes_file_sha1, untracked->ss_excludes_file.sha1); ouc->dir_flags = htonl(untracked->dir_flags); - memcpy(ouc->exclude_per_dir, untracked->exclude_per_dir, len + 1); varint_len = encode_varint(untracked->ident.len, varbuf); strbuf_add(out, varbuf, varint_len);
--
2.7.2.645.g4e1306c