path.c: fix uninitialized memory access
commit8262715b8eb157497ec1ee1cfcef778d526b2336
authorJeff King <peff@peff.net>
Tue, 3 Oct 2017 23:30:40 +0000 (3 19:30 -0400)
committerJunio C Hamano <gitster@pobox.com>
Wed, 4 Oct 2017 04:47:16 +0000 (4 13:47 +0900)
tree3acae7272c5fdf575d562ec0388bd9573b3b8abc
parent4010f1d1b782eb7585e0e0abcefa794bd5ff29a0
path.c: fix uninitialized memory access

In cleanup_path we're passing in a char array, run a memcmp on it, and
run through it without ever checking if something is in the array in the
first place.  This can lead us to access uninitialized memory, for
example in t5541-http-push-smart.sh test 7, when run under valgrind:

==4423== Conditional jump or move depends on uninitialised value(s)
==4423==    at 0x242FA9: cleanup_path (path.c:35)
==4423==    by 0x242FA9: mkpath (path.c:456)
==4423==    by 0x256CC7: refname_match (refs.c:364)
==4423==    by 0x26C181: count_refspec_match (remote.c:1015)
==4423==    by 0x26C181: match_explicit_lhs (remote.c:1126)
==4423==    by 0x26C181: check_push_refs (remote.c:1409)
==4423==    by 0x2ABB4D: transport_push (transport.c:870)
==4423==    by 0x186703: push_with_options (push.c:332)
==4423==    by 0x18746D: do_push (push.c:409)
==4423==    by 0x18746D: cmd_push (push.c:566)
==4423==    by 0x1183E0: run_builtin (git.c:352)
==4423==    by 0x11973E: handle_builtin (git.c:539)
==4423==    by 0x11973E: run_argv (git.c:593)
==4423==    by 0x11973E: main (git.c:698)
==4423==  Uninitialised value was created by a heap allocation
==4423==    at 0x4C2CD8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==4423==    by 0x4C2F195: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==4423==    by 0x2C196B: xrealloc (wrapper.c:137)
==4423==    by 0x29A30B: strbuf_grow (strbuf.c:66)
==4423==    by 0x29A30B: strbuf_vaddf (strbuf.c:277)
==4423==    by 0x242F9F: mkpath (path.c:454)
==4423==    by 0x256CC7: refname_match (refs.c:364)
==4423==    by 0x26C181: count_refspec_match (remote.c:1015)
==4423==    by 0x26C181: match_explicit_lhs (remote.c:1126)
==4423==    by 0x26C181: check_push_refs (remote.c:1409)
==4423==    by 0x2ABB4D: transport_push (transport.c:870)
==4423==    by 0x186703: push_with_options (push.c:332)
==4423==    by 0x18746D: do_push (push.c:409)
==4423==    by 0x18746D: cmd_push (push.c:566)
==4423==    by 0x1183E0: run_builtin (git.c:352)
==4423==    by 0x11973E: handle_builtin (git.c:539)
==4423==    by 0x11973E: run_argv (git.c:593)
==4423==    by 0x11973E: main (git.c:698)
==4423==

Avoid this by using skip_prefix(), which knows not to go beyond the
end of the string.

Reported-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
path.c