@matheusbsbs / matheus-bagliano / commits / 9db05711c9

apply --reject: overwrite existing `.rej` symlink if it exists

The `git apply --reject` is expected to write out `.rej` files in case one or more hunks fail to apply cleanly. Historically, the command overwrites any existing `.rej` files. The idea being that apply/reject/edit cycles are relatively common, and the generated `.rej` files are not considered precious. But the command does not overwrite existing `.rej` symbolic links, and instead follows them. This is unsafe because the same patch could potentially create such a symbolic link and point at arbitrary paths outside the current worktree, and `git apply` would write the contents of the `.rej` file into that location. Therefore, let's make sure that any existing `.rej` file or symbolic link is removed before writing it. Reported-by: RyotaK <ryotak.mail@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Junio C Hamano <gitster@pobox.com> Helped-by: Linus Torvalds <torvalds@linuxfoundation.org> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Johannes Schindelin committed Mar 9, 2023 at 16:02 UTC 9db05711c98efc14f414d4c87135a34c13586e0b
2 files changed +27 -2
apply.c
+12 -2
index d80382c940..6634e9c510 100644 --- a/apply.c +++ b/apply.c @@ -4558,7 +4558,7 @@ static int write_out_one_reject(struct apply_state *state, struct patch *patch) FILE *rej; char namebuf[PATH_MAX]; struct fragment *frag; - int cnt = 0; + int fd, cnt = 0; struct strbuf sb = STRBUF_INIT; for (cnt = 0, frag = patch->fragments; frag; frag = frag->next) { @@ -4598,7 +4598,17 @@ static int write_out_one_reject(struct apply_state *state, struct patch *patch) memcpy(namebuf, patch->new_name, cnt); memcpy(namebuf + cnt, ".rej", 5); - rej = fopen(namebuf, "w"); + fd = open(namebuf, O_CREAT | O_EXCL | O_WRONLY, 0666); + if (fd < 0) { + if (errno != EEXIST) + return error_errno(_("cannot open %s"), namebuf); + if (unlink(namebuf)) + return error_errno(_("cannot unlink '%s'"), namebuf); + fd = open(namebuf, O_CREAT | O_EXCL | O_WRONLY, 0666); + if (fd < 0) + return error_errno(_("cannot open %s"), namebuf); + } + rej = fdopen(fd, "w"); if (!rej) return error_errno(_("cannot open %s"), namebuf);
t/t4115-apply-symlink.sh
+15
index 14e0f4d705..2d03c4e4d1 100755 --- a/t/t4115-apply-symlink.sh +++ b/t/t4115-apply-symlink.sh @@ -125,4 +125,19 @@ test_expect_success SYMLINKS 'symlink escape when deleting file' ' test_path_is_file .git/delete-me ' +test_expect_success SYMLINKS '--reject removes .rej symlink if it exists' ' + test_when_finished "git reset --hard && git clean -dfx" && + + test_commit file && + echo modified >file.t && + git diff -- file.t >patch && + echo modified-again >file.t && + + ln -s foo file.t.rej && + test_must_fail git apply patch --reject 2>err && + test_i18ngrep "Rejected hunk" err && + test_path_is_missing foo && + test_path_is_file file.t.rej +' + test_done