[PATCH] diff --cc: integer overflow given a 2GB-or-larger file
- From
Jim Meyering <jim@meyering.net>
- Date
- Feb 26, 2007, 23:11 UTC
- Message-ID
- <87vehopl94.fsf@rho.meyering.net>
Few of us use git to compare or even version-control 2GB files, but when we do, we'll want it to work.
Reading a recent patch, I noticed two lines like this:
int len = st.st_size;
Instead of "int", that should be "size_t". Otherwise, in the non-symlink case, with 64-bit size_t, if the file's size is 2GB, the following xmalloc will fail:
result = xmalloc(len + 1);
trying to allocate 2^64 - 2^31 + 1 bytes (assuming sign-extension in the int-to-size_t promotion). And even if it didn't fail, the subsequent "result[len] = 0;" would be equivalent to an unpleasant "result[-2147483648] = 0;"
The other nearby "int"-declared size variable, sz, should also be of type size_t, for the same reason. If sz ever wraps around and becomes negative, xread will corrupt memory _before_ the "result" buffer.
Signed-off-by: Jim Meyering <jim@meyering.net> --- combine-diff.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/combine-diff.c b/combine-diff.c index 6b7c6be..044633d 100644 --- a/combine-diff.c +++ b/combine-diff.c @@ -684,7 +684,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent, goto deleted_file; if (S_ISLNK(st.st_mode)) { - int len = st.st_size; + size_t len = st.st_size; result_size = len; result = xmalloc(len + 1); if (result_size != readlink(elem->path, result, len)) { @@ -697,8 +697,8 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent, } else if (0 <= (fd = open(elem->path, O_RDONLY)) && !fstat(fd, &st)) { - int len = st.st_size; - int sz = 0; + size_t len = st.st_size; + size_t sz = 0; elem->mode = canon_mode(st.st_mode); result_size = len;
-- 1.5.0.1.226.g7bd59