Revision 24557209500e6ed618f04a8795a111a0c491a29c authored by Patrick Steinhardt on 01 December 2022, 14:45:23 UTC, committed by Junio C Hamano on 05 December 2022, 06:14:16 UTC
It is possible to trigger an integer overflow when parsing attribute names that are longer than 2^31 bytes because we assign the result of strlen(3P) to an `int` instead of to a `size_t`. This can lead to an abort in vsnprintf(3P) with the following reproducer: blob=$(perl -e 'print "A " . "B"x2147483648 . "\n"' | git hash-object -w --stdin) git update-index --add --cacheinfo 100644,$blob,.gitattributes git check-attr --all path BUG: strbuf.c:400: your vsnprintf is broken (returned -1) But furthermore, assuming that the attribute name is even longer than that, it can cause us to silently truncate the attribute and thus lead to wrong results. Fix this integer overflow by using a `size_t` instead. This fixes the silent truncation of attribute names, but it only partially fixes the BUG we hit: even though the initial BUG is fixed, we can still hit a BUG when parsing invalid attribute lines via `report_invalid_attr()`. This is due to an underlying design issue in vsnprintf(3P) which only knows to return an `int`, and thus it may always overflow with large inputs. This issue is benign though: the worst that can happen is that the error message is misreported to be either truncated or too long, but due to the buffer being NUL terminated we wouldn't ever do an out-of-bounds read here. Reported-by: Markus Vervier <markus.vervier@x41-dsec.de> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 8d0d48c
entry.c
#include "cache.h"
#include "blob.h"
#include "object-store.h"
#include "dir.h"
#include "streaming.h"
#include "submodule.h"
#include "progress.h"
#include "fsmonitor.h"
static void create_directories(const char *path, int path_len,
const struct checkout *state)
{
char *buf = xmallocz(path_len);
int len = 0;
while (len < path_len) {
do {
buf[len] = path[len];
len++;
} while (len < path_len && path[len] != '/');
if (len >= path_len)
break;
buf[len] = 0;
/*
* For 'checkout-index --prefix=<dir>', <dir> is
* allowed to be a symlink to an existing directory,
* and we set 'state->base_dir_len' below, such that
* we test the path components of the prefix with the
* stat() function instead of the lstat() function.
*/
if (has_dirs_only_path(buf, len, state->base_dir_len))
continue; /* ok, it is already a directory. */
/*
* If this mkdir() would fail, it could be that there
* is already a symlink or something else exists
* there, therefore we then try to unlink it and try
* one more time to create the directory.
*/
if (mkdir(buf, 0777)) {
if (errno == EEXIST && state->force &&
!unlink_or_warn(buf) && !mkdir(buf, 0777))
continue;
die_errno("cannot create directory at '%s'", buf);
}
}
free(buf);
}
static void remove_subtree(struct strbuf *path)
{
DIR *dir = opendir(path->buf);
struct dirent *de;
int origlen = path->len;
if (!dir)
die_errno("cannot opendir '%s'", path->buf);
while ((de = readdir(dir)) != NULL) {
struct stat st;
if (is_dot_or_dotdot(de->d_name))
continue;
strbuf_addch(path, '/');
strbuf_addstr(path, de->d_name);
if (lstat(path->buf, &st))
die_errno("cannot lstat '%s'", path->buf);
if (S_ISDIR(st.st_mode))
remove_subtree(path);
else if (unlink(path->buf))
die_errno("cannot unlink '%s'", path->buf);
strbuf_setlen(path, origlen);
}
closedir(dir);
if (rmdir(path->buf))
die_errno("cannot rmdir '%s'", path->buf);
}
static int create_file(const char *path, unsigned int mode)
{
mode = (mode & 0100) ? 0777 : 0666;
return open(path, O_WRONLY | O_CREAT | O_EXCL, mode);
}
static void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
{
enum object_type type;
void *blob_data = read_object_file(&ce->oid, &type, size);
if (blob_data) {
if (type == OBJ_BLOB)
return blob_data;
free(blob_data);
}
return NULL;
}
static int open_output_fd(char *path, const struct cache_entry *ce, int to_tempfile)
{
int symlink = (ce->ce_mode & S_IFMT) != S_IFREG;
if (to_tempfile) {
xsnprintf(path, TEMPORARY_FILENAME_LENGTH, "%s",
symlink ? ".merge_link_XXXXXX" : ".merge_file_XXXXXX");
return mkstemp(path);
} else {
return create_file(path, !symlink ? ce->ce_mode : 0666);
}
}
static int fstat_output(int fd, const struct checkout *state, struct stat *st)
{
/* use fstat() only when path == ce->name */
if (fstat_is_reliable() &&
state->refresh_cache && !state->base_dir_len) {
return !fstat(fd, st);
}
return 0;
}
static int streaming_write_entry(const struct cache_entry *ce, char *path,
struct stream_filter *filter,
const struct checkout *state, int to_tempfile,
int *fstat_done, struct stat *statbuf)
{
int result = 0;
int fd;
fd = open_output_fd(path, ce, to_tempfile);
if (fd < 0)
return -1;
result |= stream_blob_to_fd(fd, &ce->oid, filter, 1);
*fstat_done = fstat_output(fd, state, statbuf);
result |= close(fd);
if (result)
unlink(path);
return result;
}
void enable_delayed_checkout(struct checkout *state)
{
if (!state->delayed_checkout) {
state->delayed_checkout = xmalloc(sizeof(*state->delayed_checkout));
state->delayed_checkout->state = CE_CAN_DELAY;
string_list_init(&state->delayed_checkout->filters, 0);
string_list_init(&state->delayed_checkout->paths, 0);
}
}
static int remove_available_paths(struct string_list_item *item, void *cb_data)
{
struct string_list *available_paths = cb_data;
struct string_list_item *available;
available = string_list_lookup(available_paths, item->string);
if (available)
available->util = (void *)item->string;
return !available;
}
int finish_delayed_checkout(struct checkout *state, int *nr_checkouts)
{
int errs = 0;
unsigned delayed_object_count;
off_t filtered_bytes = 0;
struct string_list_item *filter, *path;
struct progress *progress;
struct delayed_checkout *dco = state->delayed_checkout;
if (!state->delayed_checkout)
return errs;
dco->state = CE_RETRY;
delayed_object_count = dco->paths.nr;
progress = start_delayed_progress(_("Filtering content"), delayed_object_count);
while (dco->filters.nr > 0) {
for_each_string_list_item(filter, &dco->filters) {
struct string_list available_paths = STRING_LIST_INIT_NODUP;
display_progress(progress, delayed_object_count - dco->paths.nr);
if (!async_query_available_blobs(filter->string, &available_paths)) {
/* Filter reported an error */
errs = 1;
filter->string = "";
continue;
}
if (available_paths.nr <= 0) {
/*
* Filter responded with no entries. That means
* the filter is done and we can remove the
* filter from the list (see
* "string_list_remove_empty_items" call below).
*/
filter->string = "";
continue;
}
/*
* In dco->paths we store a list of all delayed paths.
* The filter just send us a list of available paths.
* Remove them from the list.
*/
filter_string_list(&dco->paths, 0,
&remove_available_paths, &available_paths);
for_each_string_list_item(path, &available_paths) {
struct cache_entry* ce;
if (!path->util) {
error("external filter '%s' signaled that '%s' "
"is now available although it has not been "
"delayed earlier",
filter->string, path->string);
errs |= 1;
/*
* Do not ask the filter for available blobs,
* again, as the filter is likely buggy.
*/
filter->string = "";
continue;
}
ce = index_file_exists(state->istate, path->string,
strlen(path->string), 0);
if (ce) {
errs |= checkout_entry(ce, state, NULL, nr_checkouts);
filtered_bytes += ce->ce_stat_data.sd_size;
display_throughput(progress, filtered_bytes);
} else
errs = 1;
}
}
string_list_remove_empty_items(&dco->filters, 0);
}
stop_progress(&progress);
string_list_clear(&dco->filters, 0);
/* At this point we should not have any delayed paths anymore. */
errs |= dco->paths.nr;
for_each_string_list_item(path, &dco->paths) {
error("'%s' was not filtered properly", path->string);
}
string_list_clear(&dco->paths, 0);
free(dco);
state->delayed_checkout = NULL;
return errs;
}
static int write_entry(struct cache_entry *ce,
char *path, const struct checkout *state, int to_tempfile)
{
unsigned int ce_mode_s_ifmt = ce->ce_mode & S_IFMT;
struct delayed_checkout *dco = state->delayed_checkout;
int fd, ret, fstat_done = 0;
char *new_blob;
struct strbuf buf = STRBUF_INIT;
unsigned long size;
ssize_t wrote;
size_t newsize = 0;
struct stat st;
const struct submodule *sub;
struct checkout_metadata meta;
clone_checkout_metadata(&meta, &state->meta, &ce->oid);
if (ce_mode_s_ifmt == S_IFREG) {
struct stream_filter *filter = get_stream_filter(state->istate, ce->name,
&ce->oid);
if (filter &&
!streaming_write_entry(ce, path, filter,
state, to_tempfile,
&fstat_done, &st))
goto finish;
}
switch (ce_mode_s_ifmt) {
case S_IFLNK:
new_blob = read_blob_entry(ce, &size);
if (!new_blob)
return error("unable to read sha1 file of %s (%s)",
path, oid_to_hex(&ce->oid));
/*
* We can't make a real symlink; write out a regular file entry
* with the symlink destination as its contents.
*/
if (!has_symlinks || to_tempfile)
goto write_file_entry;
ret = symlink(new_blob, path);
free(new_blob);
if (ret)
return error_errno("unable to create symlink %s", path);
break;
case S_IFREG:
/*
* We do not send the blob in case of a retry, so do not
* bother reading it at all.
*/
if (dco && dco->state == CE_RETRY) {
new_blob = NULL;
size = 0;
} else {
new_blob = read_blob_entry(ce, &size);
if (!new_blob)
return error("unable to read sha1 file of %s (%s)",
path, oid_to_hex(&ce->oid));
}
/*
* Convert from git internal format to working tree format
*/
if (dco && dco->state != CE_NO_DELAY) {
ret = async_convert_to_working_tree(state->istate, ce->name, new_blob,
size, &buf, &meta, dco);
if (ret && string_list_has_string(&dco->paths, ce->name)) {
free(new_blob);
goto delayed;
}
} else
ret = convert_to_working_tree(state->istate, ce->name, new_blob, size, &buf, &meta);
if (ret) {
free(new_blob);
new_blob = strbuf_detach(&buf, &newsize);
size = newsize;
}
/*
* No "else" here as errors from convert are OK at this
* point. If the error would have been fatal (e.g.
* filter is required), then we would have died already.
*/
write_file_entry:
fd = open_output_fd(path, ce, to_tempfile);
if (fd < 0) {
free(new_blob);
return error_errno("unable to create file %s", path);
}
wrote = write_in_full(fd, new_blob, size);
if (!to_tempfile)
fstat_done = fstat_output(fd, state, &st);
close(fd);
free(new_blob);
if (wrote < 0)
return error("unable to write file %s", path);
break;
case S_IFGITLINK:
if (to_tempfile)
return error("cannot create temporary submodule %s", path);
if (mkdir(path, 0777) < 0)
return error("cannot create submodule directory %s", path);
sub = submodule_from_ce(ce);
if (sub)
return submodule_move_head(ce->name,
NULL, oid_to_hex(&ce->oid),
state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
break;
default:
return error("unknown file mode for %s in index", path);
}
finish:
if (state->refresh_cache) {
assert(state->istate);
if (!fstat_done)
if (lstat(ce->name, &st) < 0)
return error_errno("unable to stat just-written file %s",
ce->name);
fill_stat_cache_info(state->istate, ce, &st);
ce->ce_flags |= CE_UPDATE_IN_BASE;
mark_fsmonitor_invalid(state->istate, ce);
state->istate->cache_changed |= CE_ENTRY_CHANGED;
}
delayed:
return 0;
}
/*
* This is like 'lstat()', except it refuses to follow symlinks
* in the path, after skipping "skiplen".
*/
static int check_path(const char *path, int len, struct stat *st, int skiplen)
{
const char *slash = path + len;
while (path < slash && *slash != '/')
slash--;
if (!has_dirs_only_path(path, slash - path, skiplen)) {
errno = ENOENT;
return -1;
}
return lstat(path, st);
}
static void mark_colliding_entries(const struct checkout *state,
struct cache_entry *ce, struct stat *st)
{
int i, trust_ino = check_stat;
#if defined(GIT_WINDOWS_NATIVE) || defined(__CYGWIN__)
trust_ino = 0;
#endif
ce->ce_flags |= CE_MATCHED;
for (i = 0; i < state->istate->cache_nr; i++) {
struct cache_entry *dup = state->istate->cache[i];
if (dup == ce)
break;
if (dup->ce_flags & (CE_MATCHED | CE_VALID | CE_SKIP_WORKTREE))
continue;
if ((trust_ino && !match_stat_data(&dup->ce_stat_data, st)) ||
(!trust_ino && !fspathcmp(ce->name, dup->name))) {
dup->ce_flags |= CE_MATCHED;
break;
}
}
}
/*
* Write the contents from ce out to the working tree.
*
* When topath[] is not NULL, instead of writing to the working tree
* file named by ce, a temporary file is created by this function and
* its name is returned in topath[], which must be able to hold at
* least TEMPORARY_FILENAME_LENGTH bytes long.
*/
int checkout_entry(struct cache_entry *ce, const struct checkout *state,
char *topath, int *nr_checkouts)
{
static struct strbuf path = STRBUF_INIT;
struct stat st;
if (ce->ce_flags & CE_WT_REMOVE) {
if (topath)
/*
* No content and thus no path to create, so we have
* no pathname to return.
*/
BUG("Can't remove entry to a path");
unlink_entry(ce);
return 0;
}
if (topath)
return write_entry(ce, topath, state, 1);
strbuf_reset(&path);
strbuf_add(&path, state->base_dir, state->base_dir_len);
strbuf_add(&path, ce->name, ce_namelen(ce));
if (!check_path(path.buf, path.len, &st, state->base_dir_len)) {
const struct submodule *sub;
unsigned changed = ie_match_stat(state->istate, ce, &st,
CE_MATCH_IGNORE_VALID | CE_MATCH_IGNORE_SKIP_WORKTREE);
/*
* Needs to be checked before !changed returns early,
* as the possibly empty directory was not changed
*/
sub = submodule_from_ce(ce);
if (sub) {
int err;
if (!is_submodule_populated_gently(ce->name, &err)) {
struct stat sb;
if (lstat(ce->name, &sb))
die(_("could not stat file '%s'"), ce->name);
if (!(st.st_mode & S_IFDIR))
unlink_or_warn(ce->name);
return submodule_move_head(ce->name,
NULL, oid_to_hex(&ce->oid), 0);
} else
return submodule_move_head(ce->name,
"HEAD", oid_to_hex(&ce->oid),
state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
}
if (!changed)
return 0;
if (!state->force) {
if (!state->quiet)
fprintf(stderr,
"%s already exists, no checkout\n",
path.buf);
return -1;
}
if (state->clone)
mark_colliding_entries(state, ce, &st);
/*
* We unlink the old file, to get the new one with the
* right permissions (including umask, which is nasty
* to emulate by hand - much easier to let the system
* just do the right thing)
*/
if (S_ISDIR(st.st_mode)) {
/* If it is a gitlink, leave it alone! */
if (S_ISGITLINK(ce->ce_mode))
return 0;
remove_subtree(&path);
} else if (unlink(path.buf))
return error_errno("unable to unlink old '%s'", path.buf);
} else if (state->not_new)
return 0;
create_directories(path.buf, path.len, state);
if (nr_checkouts)
(*nr_checkouts)++;
return write_entry(ce, path.buf, state, 0);
}
void unlink_entry(const struct cache_entry *ce)
{
const struct submodule *sub = submodule_from_ce(ce);
if (sub) {
/* state.force is set at the caller. */
submodule_move_head(ce->name, "HEAD", NULL,
SUBMODULE_MOVE_HEAD_FORCE);
}
if (!check_leading_path(ce->name, ce_namelen(ce)))
return;
if (remove_or_warn(ce->ce_mode, ce->name))
return;
schedule_dir_for_removal(ce->name, ce_namelen(ce));
}
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