From c5fe29f696f4a490dfdc4dbc75319076baf36def Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 30 Jan 2025 07:17:38 +0100 Subject: [PATCH 1/2] unix-socket: fix memory leak when chdir(3p) fails When trying to create a Unix socket in a path that exceeds the maximum socket name length we try to first change the directory into the parent folder before creating the socket to reduce the length of the name. When this fails we error out of `unix_sockaddr_init()` with an error code, which indicates to the caller that the context has not been initialized. Consequently, they don't release that context. This leads to a memory leak: when we have already populated the context with the original directory that we need to chdir(3p) back into, but then the chdir(3p) into the socket's parent directory fails, then we won't release the original directory's path. The leak is exposed by t0301, but only when running tests in a directory hierarchy whose path is long enough to make the socket name length exceed the maximum socket name length: Direct leak of 129 byte(s) in 1 object(s) allocated from: #0 0x5555555e85c6 in realloc.part.0 lsan_interceptors.cpp.o #1 0x55555590e3d6 in xrealloc ../wrapper.c:140:8 #2 0x5555558c8fc6 in strbuf_grow ../strbuf.c:114:2 #3 0x5555558cacab in strbuf_getcwd ../strbuf.c:605:3 #4 0x555555923ff6 in unix_sockaddr_init ../unix-socket.c:65:7 #5 0x555555923e42 in unix_stream_connect ../unix-socket.c:84:6 #6 0x55555562a984 in send_request ../builtin/credential-cache.c:46:11 #7 0x55555562a89e in do_cache ../builtin/credential-cache.c:108:6 #8 0x55555562a655 in cmd_credential_cache ../builtin/credential-cache.c:178:3 #9 0x555555700547 in run_builtin ../git.c:480:11 #10 0x5555556ff0e0 in handle_builtin ../git.c:740:9 #11 0x5555556ffee8 in run_argv ../git.c:807:4 #12 0x5555556fee6b in cmd_main ../git.c:947:19 #13 0x55555593f689 in main ../common-main.c:64:11 #14 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0) #15 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0) #16 0x5555555ad1d4 in _start (git+0x591d4) DEDUP_TOKEN: ___interceptor_realloc.part.0--xrealloc--strbuf_grow--strbuf_getcwd--unix_sockaddr_init--unix_stream_connect--send_request--do_cache--cmd_credential_cache--run_builtin--handle_builtin--run_argv--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start SUMMARY: LeakSanitizer: 129 byte(s) leaked in 1 allocation(s). Fix this leak. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- unix-socket.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/unix-socket.c b/unix-socket.c index 79800d8063..9a21ade5d8 100644 --- a/unix-socket.c +++ b/unix-socket.c @@ -63,8 +63,10 @@ static int unix_sockaddr_init(struct sockaddr_un *sa, const char *path, if (strbuf_getcwd(&cwd)) return -1; ctx->orig_dir = strbuf_detach(&cwd, NULL); - if (chdir_len(dir, slash - dir) < 0) + if (chdir_len(dir, slash - dir) < 0) { + FREE_AND_NULL(ctx->orig_dir); return -1; + } } memset(sa, 0, sizeof(*sa)); From 087740d65a5d28756ecbe56fc3b10328b52e8d33 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 30 Jan 2025 07:17:39 +0100 Subject: [PATCH 2/2] scalar: free result of `remote_default_branch()` We don't free the result of `remote_default_branch()`, leading to a memory leak. This leak is exposed by t9211, but only when run with Meson with the `-Db_sanitize=leak` option: Direct leak of 5 byte(s) in 1 object(s) allocated from: #0 0x5555555cfb93 in malloc (scalar+0x7bb93) #1 0x5555556b05c2 in do_xmalloc ../wrapper.c:55:8 #2 0x5555556b06c4 in do_xmallocz ../wrapper.c:89:8 #3 0x5555556b0656 in xmallocz ../wrapper.c:97:9 #4 0x5555556b0728 in xmemdupz ../wrapper.c:113:16 #5 0x5555556b07a7 in xstrndup ../wrapper.c:119:9 #6 0x5555555d3a4b in remote_default_branch ../scalar.c:338:14 #7 0x5555555d20e6 in cmd_clone ../scalar.c:493:28 #8 0x5555555d196b in cmd_main ../scalar.c:992:14 #9 0x5555557c4059 in main ../common-main.c:64:11 #10 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0) #11 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0) #12 0x555555592054 in _start (scalar+0x3e054) DEDUP_TOKEN: __interceptor_malloc--do_xmalloc--do_xmallocz--xmallocz--xmemdupz--xstrndup--remote_default_branch--cmd_clone--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start SUMMARY: LeakSanitizer: 5 byte(s) leaked in 1 allocation(s). As the `branch` variable may contain a string constant obtained from parsing command line arguments we cannot free the leaking variable directly. Instead, introduce a new `branch_to_free` variable that only ever gets assigned the allocated string and free that one to plug the leak. It is unclear why the leak isn't flagged when running the test via our Makefile. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- scalar.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/scalar.c b/scalar.c index fb2940c2a0..6c47afa4ea 100644 --- a/scalar.c +++ b/scalar.c @@ -408,6 +408,7 @@ void load_builtin_commands(const char *prefix, struct cmdnames *cmds) static int cmd_clone(int argc, const char **argv) { const char *branch = NULL; + char *branch_to_free = NULL; int full_clone = 0, single_branch = 0, show_progress = isatty(2); int src = 1; struct option clone_options[] = { @@ -487,7 +488,7 @@ static int cmd_clone(int argc, const char **argv) /* common-main already logs `argv` */ trace2_def_repo(the_repository); - if (!branch && !(branch = remote_default_branch(url))) { + if (!branch && !(branch = branch_to_free = remote_default_branch(url))) { res = error(_("failed to get default branch for '%s'"), url); goto cleanup; } @@ -542,6 +543,7 @@ static int cmd_clone(int argc, const char **argv) res = register_dir(); cleanup: + free(branch_to_free); free(enlistment); free(dir); strbuf_release(&buf);