From 2944a94c6b74d3941f63d1f4eee5bdfbbf5cd400 Mon Sep 17 00:00:00 2001 From: Johannes Sixt Date: Tue, 3 Oct 2017 22:24:57 +0200 Subject: [PATCH] sub-process: use child_process.args instead of child_process.argv Currently the argv is only allocated on the stack, and then assigned to process->argv. When the start_subprocess function goes out of scope, the local argv variable is eliminated from the stack, but the pointer is still kept around in process->argv. Much later when we try to access the same process->argv in finish_command, this leads us to access a memory location that no longer contains what we want. As argv0 is only used for printing errors, this is not easily noticed in normal git operations. However when running t0021-conversion.sh through valgrind, valgrind rightfully complains: ==21024== Invalid read of size 8 ==21024== at 0x2ACF64: finish_command (run-command.c:869) ==21024== by 0x2D6B18: subprocess_exit_handler (sub-process.c:72) ==21024== by 0x2AB41E: cleanup_children (run-command.c:45) ==21024== by 0x2AB526: cleanup_children_on_exit (run-command.c:81) ==21024== by 0x54AD487: __run_exit_handlers (in /usr/lib/libc-2.26.so) ==21024== by 0x54AD4D9: exit (in /usr/lib/libc-2.26.so) ==21024== by 0x11A9EF: handle_builtin (git.c:550) ==21024== by 0x11ABCC: run_argv (git.c:602) ==21024== by 0x11AD8E: cmd_main (git.c:679) ==21024== by 0x1BF125: main (common-main.c:43) ==21024== Address 0x1ffeffec00 is on thread 1's stack ==21024== 1504 bytes below stack pointer ==21024== These days, the child_process structure has its own args array, and the standard way to set up its argv[] is to use that one, instead of assigning to process->argv to point at an array that is outside. Use that facility automatically fixes this issue. Reported-by: Thomas Gummerer Signed-off-by: Johannes Sixt Signed-off-by: Junio C Hamano --- sub-process.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/sub-process.c b/sub-process.c index fcc4832c14..648b3a3943 100644 --- a/sub-process.c +++ b/sub-process.c @@ -74,13 +74,12 @@ int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, co { int err; struct child_process *process; - const char *argv[] = { cmd, NULL }; entry->cmd = cmd; process = &entry->process; child_process_init(process); - process->argv = argv; + argv_array_push(&process->args, cmd); process->use_shell = 1; process->in = -1; process->out = -1; -- 2.11.4.GIT