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
server-info.c
#include "cache.h"
#include "dir.h"
#include "repository.h"
#include "refs.h"
#include "object.h"
#include "commit.h"
#include "tag.h"
#include "packfile.h"
#include "object-store.h"
#include "strbuf.h"
struct update_info_ctx {
FILE *cur_fp;
FILE *old_fp; /* becomes NULL if it differs from cur_fp */
struct strbuf cur_sb;
struct strbuf old_sb;
};
static void uic_mark_stale(struct update_info_ctx *uic)
{
fclose(uic->old_fp);
uic->old_fp = NULL;
}
static int uic_is_stale(const struct update_info_ctx *uic)
{
return uic->old_fp == NULL;
}
static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
{
va_list ap;
int ret = -1;
va_start(ap, fmt);
if (uic_is_stale(uic)) {
ret = vfprintf(uic->cur_fp, fmt, ap);
} else {
ssize_t r;
struct strbuf *cur = &uic->cur_sb;
struct strbuf *old = &uic->old_sb;
strbuf_reset(cur);
strbuf_vinsertf(cur, 0, fmt, ap);
strbuf_reset(old);
strbuf_grow(old, cur->len);
r = fread(old->buf, 1, cur->len, uic->old_fp);
if (r != cur->len || memcmp(old->buf, cur->buf, r))
uic_mark_stale(uic);
if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
ret = 0;
}
va_end(ap);
return ret;
}
/*
* Create the file "path" by writing to a temporary file and renaming
* it into place. The contents of the file come from "generate", which
* should return non-zero if it encounters an error.
*/
static int update_info_file(char *path,
int (*generate)(struct update_info_ctx *),
int force)
{
char *tmp = mkpathdup("%s_XXXXXX", path);
int ret = -1;
int fd = -1;
FILE *to_close;
struct update_info_ctx uic = {
.cur_fp = NULL,
.old_fp = NULL,
.cur_sb = STRBUF_INIT,
.old_sb = STRBUF_INIT
};
safe_create_leading_directories(path);
fd = git_mkstemp_mode(tmp, 0666);
if (fd < 0)
goto out;
to_close = uic.cur_fp = fdopen(fd, "w");
if (!uic.cur_fp)
goto out;
fd = -1;
/* no problem on ENOENT and old_fp == NULL, it's stale, now */
if (!force)
uic.old_fp = fopen_or_warn(path, "r");
/*
* uic_printf will compare incremental comparison against old_fp
* and mark uic as stale if needed
*/
ret = generate(&uic);
if (ret)
goto out;
/* new file may be shorter than the old one, check here */
if (!uic_is_stale(&uic)) {
struct stat st;
long new_len = ftell(uic.cur_fp);
int old_fd = fileno(uic.old_fp);
if (new_len < 0) {
ret = -1;
goto out;
}
if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
uic_mark_stale(&uic);
}
uic.cur_fp = NULL;
if (fclose(to_close))
goto out;
if (uic_is_stale(&uic)) {
if (adjust_shared_perm(tmp) < 0)
goto out;
if (rename(tmp, path) < 0)
goto out;
} else {
unlink(tmp);
}
ret = 0;
out:
if (ret) {
error_errno("unable to update %s", path);
if (uic.cur_fp)
fclose(uic.cur_fp);
else if (fd >= 0)
close(fd);
unlink(tmp);
}
free(tmp);
if (uic.old_fp)
fclose(uic.old_fp);
strbuf_release(&uic.old_sb);
strbuf_release(&uic.cur_sb);
return ret;
}
static int add_info_ref(const char *path, const struct object_id *oid,
int flag, void *cb_data)
{
struct update_info_ctx *uic = cb_data;
struct object *o = parse_object(the_repository, oid);
if (!o)
return -1;
if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
return -1;
if (o->type == OBJ_TAG) {
o = deref_tag(the_repository, o, path, 0);
if (o)
if (uic_printf(uic, "%s %s^{}\n",
oid_to_hex(&o->oid), path) < 0)
return -1;
}
return 0;
}
static int generate_info_refs(struct update_info_ctx *uic)
{
return for_each_ref(add_info_ref, uic);
}
static int update_info_refs(int force)
{
char *path = git_pathdup("info/refs");
int ret = update_info_file(path, generate_info_refs, force);
free(path);
return ret;
}
/* packs */
static struct pack_info {
struct packed_git *p;
int old_num;
int new_num;
} **info;
static int num_pack;
static struct pack_info *find_pack_by_name(const char *name)
{
int i;
for (i = 0; i < num_pack; i++) {
struct packed_git *p = info[i]->p;
if (!strcmp(pack_basename(p), name))
return info[i];
}
return NULL;
}
/* Returns non-zero when we detect that the info in the
* old file is useless.
*/
static int parse_pack_def(const char *packname, int old_cnt)
{
struct pack_info *i = find_pack_by_name(packname);
if (i) {
i->old_num = old_cnt;
return 0;
}
else {
/* The file describes a pack that is no longer here */
return 1;
}
}
/* Returns non-zero when we detect that the info in the
* old file is useless.
*/
static int read_pack_info_file(const char *infofile)
{
FILE *fp;
struct strbuf line = STRBUF_INIT;
int old_cnt = 0;
int stale = 1;
fp = fopen_or_warn(infofile, "r");
if (!fp)
return 1; /* nonexistent is not an error. */
while (strbuf_getline(&line, fp) != EOF) {
const char *arg;
if (!line.len)
continue;
if (skip_prefix(line.buf, "P ", &arg)) {
/* P name */
if (parse_pack_def(arg, old_cnt++))
goto out_stale;
} else if (line.buf[0] == 'D') {
/* we used to emit D but that was misguided. */
goto out_stale;
} else if (line.buf[0] == 'T') {
/* we used to emit T but nobody uses it. */
goto out_stale;
} else {
error("unrecognized: %s", line.buf);
}
}
stale = 0;
out_stale:
strbuf_release(&line);
fclose(fp);
return stale;
}
static int compare_info(const void *a_, const void *b_)
{
struct pack_info *const *a = a_;
struct pack_info *const *b = b_;
if (0 <= (*a)->old_num && 0 <= (*b)->old_num)
/* Keep the order in the original */
return (*a)->old_num - (*b)->old_num;
else if (0 <= (*a)->old_num)
/* Only A existed in the original so B is obviously newer */
return -1;
else if (0 <= (*b)->old_num)
/* The other way around. */
return 1;
/* then it does not matter but at least keep the comparison stable */
if ((*a)->p == (*b)->p)
return 0;
else if ((*a)->p < (*b)->p)
return -1;
else
return 1;
}
static void init_pack_info(const char *infofile, int force)
{
struct packed_git *p;
int stale;
int i;
size_t alloc = 0;
for (p = get_all_packs(the_repository); p; p = p->next) {
/* we ignore things on alternate path since they are
* not available to the pullers in general.
*/
if (!p->pack_local || !file_exists(p->pack_name))
continue;
i = num_pack++;
ALLOC_GROW(info, num_pack, alloc);
info[i] = xcalloc(1, sizeof(struct pack_info));
info[i]->p = p;
info[i]->old_num = -1;
}
if (infofile && !force)
stale = read_pack_info_file(infofile);
else
stale = 1;
for (i = 0; i < num_pack; i++)
if (stale)
info[i]->old_num = -1;
/* renumber them */
QSORT(info, num_pack, compare_info);
for (i = 0; i < num_pack; i++)
info[i]->new_num = i;
}
static void free_pack_info(void)
{
int i;
for (i = 0; i < num_pack; i++)
free(info[i]);
free(info);
}
static int write_pack_info_file(struct update_info_ctx *uic)
{
int i;
for (i = 0; i < num_pack; i++) {
if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
return -1;
}
if (uic_printf(uic, "\n") < 0)
return -1;
return 0;
}
static int update_info_packs(int force)
{
char *infofile = mkpathdup("%s/info/packs", get_object_directory());
int ret;
init_pack_info(infofile, force);
ret = update_info_file(infofile, write_pack_info_file, force);
free_pack_info();
free(infofile);
return ret;
}
/* public */
int update_server_info(int force)
{
/* We would add more dumb-server support files later,
* including index of available pack files and their
* intended audiences.
*/
int errs = 0;
errs = errs | update_info_refs(force);
errs = errs | update_info_packs(force);
/* remove leftover rev-cache file if there is any */
unlink_or_warn(git_path("info/rev-cache"));
return errs;
}
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