[PATCH 1/2] gpg-interface: handle missing " with " gracefully in parse_ssh_output()
From: René Scharfe <hidden>
Date: 2021-10-30 17:05:05
Subsystem:
the rest · Maintainer:
Linus Torvalds
If the output of ssh-keygen starts with "Good \"git\" signature for ", but is not followed by " with " for some reason, then parse_ssh_output() uses -1 as the len parameter of xmemdupz(), which in turn will end the program. Reject the signature and carry on instead in that case. Signed-off-by: René Scharfe <redacted> --- This code was added after v2.33.0. Patch formatted with --inter-hunk-context=2 for easier review. Silly bonus question: What's the purpose of the "+ 1" and "- 1", which seem to cancel each other out? gpg-interface.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/gpg-interface.c b/gpg-interface.c
index 800d8caa67..62d340e78a 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c@@ -387,17 +387,19 @@ static void parse_ssh_output(struct signature_check *sigc) line = to_free = xmemdupz(sigc->output, strcspn(sigc->output, "\n")); if (skip_prefix(line, "Good \"git\" signature for ", &line)) { - /* Valid signature and known principal */ - sigc->result = 'G'; - sigc->trust_level = TRUST_FULLY; - /* Search for the last "with" to get the full principal */ principal = line; do { search = strstr(line, " with "); if (search) line = search + 1; } while (search != NULL); + if (line == principal) + goto cleanup; + + /* Valid signature and known principal */ + sigc->result = 'G'; + sigc->trust_level = TRUST_FULLY; sigc->signer = xmemdupz(principal, line - principal - 1); } else if (skip_prefix(line, "Good \"git\" signature with ", &line)) { /* Valid signature, but key unknown */ --
2.33.1