Revision 447ac906e189535e77dcb1f4bbe3f1bc917d4c12 authored by Patrick Steinhardt on 01 December 2022, 14:45:31 UTC, committed by Junio C Hamano on 05 December 2022, 06:14:16 UTC
The `struct attr_stack` tracks the stack of all patterns together with their attributes. When parsing a gitattributes file that has more than 2^31 such patterns though we may trigger multiple out-of-bounds reads on 64 bit platforms. This is because while the `num_matches` variable is an unsigned integer, we always use a signed integer to iterate over them. I have not been able to reproduce this issue due to memory constraints on my systems. But despite the out-of-bounds reads, the worst thing that can seemingly happen is to call free(3P) with a garbage pointer when calling `attr_stack_free()`. Fix this bug by using unsigned integers to iterate over the array. While this makes the iteration somewhat awkward when iterating in reverse, it is at least better than knowingly running into an out-of-bounds read. While at it, convert the call to `ALLOC_GROW` to use `ALLOC_GROW_BY` instead. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 34ace8b
dir-iterator.c
#include "cache.h"
#include "dir.h"
#include "iterator.h"
#include "dir-iterator.h"
struct dir_iterator_level {
DIR *dir;
/*
* The length of the directory part of path at this level
* (including a trailing '/'):
*/
size_t prefix_len;
};
/*
* The full data structure used to manage the internal directory
* iteration state. It includes members that are not part of the
* public interface.
*/
struct dir_iterator_int {
struct dir_iterator base;
/*
* The number of levels currently on the stack. After the first
* call to dir_iterator_begin(), if it succeeds to open the
* first level's dir, this will always be at least 1. Then,
* when it comes to zero the iteration is ended and this
* struct is freed.
*/
size_t levels_nr;
/* The number of levels that have been allocated on the stack */
size_t levels_alloc;
/*
* A stack of levels. levels[0] is the uppermost directory
* that will be included in this iteration.
*/
struct dir_iterator_level *levels;
/* Combination of flags for this dir-iterator */
unsigned int flags;
};
/*
* Push a level in the iter stack and initialize it with information from
* the directory pointed by iter->base->path. It is assumed that this
* strbuf points to a valid directory path. Return 0 on success and -1
* otherwise, setting errno accordingly and leaving the stack unchanged.
*/
static int push_level(struct dir_iterator_int *iter)
{
struct dir_iterator_level *level;
ALLOC_GROW(iter->levels, iter->levels_nr + 1, iter->levels_alloc);
level = &iter->levels[iter->levels_nr++];
if (!is_dir_sep(iter->base.path.buf[iter->base.path.len - 1]))
strbuf_addch(&iter->base.path, '/');
level->prefix_len = iter->base.path.len;
level->dir = opendir(iter->base.path.buf);
if (!level->dir) {
int saved_errno = errno;
if (errno != ENOENT) {
warning_errno("error opening directory '%s'",
iter->base.path.buf);
}
iter->levels_nr--;
errno = saved_errno;
return -1;
}
return 0;
}
/*
* Pop the top level on the iter stack, releasing any resources associated
* with it. Return the new value of iter->levels_nr.
*/
static int pop_level(struct dir_iterator_int *iter)
{
struct dir_iterator_level *level =
&iter->levels[iter->levels_nr - 1];
if (level->dir && closedir(level->dir))
warning_errno("error closing directory '%s'",
iter->base.path.buf);
level->dir = NULL;
return --iter->levels_nr;
}
/*
* Populate iter->base with the necessary information on the next iteration
* entry, represented by the given dirent de. Return 0 on success and -1
* otherwise, setting errno accordingly.
*/
static int prepare_next_entry_data(struct dir_iterator_int *iter,
struct dirent *de)
{
int err, saved_errno;
strbuf_addstr(&iter->base.path, de->d_name);
/*
* We have to reset these because the path strbuf might have
* been realloc()ed at the previous strbuf_addstr().
*/
iter->base.relative_path = iter->base.path.buf +
iter->levels[0].prefix_len;
iter->base.basename = iter->base.path.buf +
iter->levels[iter->levels_nr - 1].prefix_len;
if (iter->flags & DIR_ITERATOR_FOLLOW_SYMLINKS)
err = stat(iter->base.path.buf, &iter->base.st);
else
err = lstat(iter->base.path.buf, &iter->base.st);
saved_errno = errno;
if (err && errno != ENOENT)
warning_errno("failed to stat '%s'", iter->base.path.buf);
errno = saved_errno;
return err;
}
int dir_iterator_advance(struct dir_iterator *dir_iterator)
{
struct dir_iterator_int *iter =
(struct dir_iterator_int *)dir_iterator;
if (S_ISDIR(iter->base.st.st_mode) && push_level(iter)) {
if (errno != ENOENT && iter->flags & DIR_ITERATOR_PEDANTIC)
goto error_out;
if (iter->levels_nr == 0)
goto error_out;
}
/* Loop until we find an entry that we can give back to the caller. */
while (1) {
struct dirent *de;
struct dir_iterator_level *level =
&iter->levels[iter->levels_nr - 1];
strbuf_setlen(&iter->base.path, level->prefix_len);
errno = 0;
de = readdir(level->dir);
if (!de) {
if (errno) {
warning_errno("error reading directory '%s'",
iter->base.path.buf);
if (iter->flags & DIR_ITERATOR_PEDANTIC)
goto error_out;
} else if (pop_level(iter) == 0) {
return dir_iterator_abort(dir_iterator);
}
continue;
}
if (is_dot_or_dotdot(de->d_name))
continue;
if (prepare_next_entry_data(iter, de)) {
if (errno != ENOENT && iter->flags & DIR_ITERATOR_PEDANTIC)
goto error_out;
continue;
}
return ITER_OK;
}
error_out:
dir_iterator_abort(dir_iterator);
return ITER_ERROR;
}
int dir_iterator_abort(struct dir_iterator *dir_iterator)
{
struct dir_iterator_int *iter = (struct dir_iterator_int *)dir_iterator;
for (; iter->levels_nr; iter->levels_nr--) {
struct dir_iterator_level *level =
&iter->levels[iter->levels_nr - 1];
if (level->dir && closedir(level->dir)) {
int saved_errno = errno;
strbuf_setlen(&iter->base.path, level->prefix_len);
errno = saved_errno;
warning_errno("error closing directory '%s'",
iter->base.path.buf);
}
}
free(iter->levels);
strbuf_release(&iter->base.path);
free(iter);
return ITER_DONE;
}
struct dir_iterator *dir_iterator_begin(const char *path, unsigned int flags)
{
struct dir_iterator_int *iter = xcalloc(1, sizeof(*iter));
struct dir_iterator *dir_iterator = &iter->base;
int saved_errno;
strbuf_init(&iter->base.path, PATH_MAX);
strbuf_addstr(&iter->base.path, path);
ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
iter->levels_nr = 0;
iter->flags = flags;
/*
* Note: stat already checks for NULL or empty strings and
* inexistent paths.
*/
if (stat(iter->base.path.buf, &iter->base.st) < 0) {
saved_errno = errno;
goto error_out;
}
if (!S_ISDIR(iter->base.st.st_mode)) {
saved_errno = ENOTDIR;
goto error_out;
}
return dir_iterator;
error_out:
dir_iterator_abort(dir_iterator);
errno = saved_errno;
return NULL;
}
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