[PATCH v2] mailinfo: fix pointential memory leak if `decode_header` failed

From: Lidong Yan <502024330056@smail.nju.edu.cn>

In mailinfo.c:decode_header, if convert_to_utf8 failed, the strbuf stored in dec will leak. Simply add strbuf_release and free(dec) will solve this problem.

Signed-off-by: Lidong Yan <502024330056@smail.nju.edu.cn>
---
    decode_header: fix pointential memory leak if decode_header failed
    
    In mailinfo.c line 539, if convert_to_utf8 failed, the strbuf stored in
    dec will leak. Simply add strbuf_release and free(dec) will solve this
    problem.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1956%2Fbrandb97%2Ffix-mailinfo-decode-header-leak-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1956/brandb97/fix-mailinfo-decode-header-leak-v2
Pull-Request: https://github.com/git/git/pull/1956

Range-diff vs v1:

 1:  81fdfb94315 ! 1:  90dc9b0d49b decode_header: fix pointential memory leak if decode_header failed
     @@ Metadata
      Author: Lidong Yan <502024330056@smail.nju.edu.cn>
      
       ## Commit message ##
     -    decode_header: fix pointential memory leak if decode_header failed
     +    mailinfo: fix pointential memory leak if `decode_header` failed
      
     -    In mailinfo.c line 539, if convert_to_utf8 failed, the strbuf stored
     +    In mailinfo.c:decode_header, if convert_to_utf8 failed, the strbuf stored
          in dec will leak. Simply add strbuf_release and free(dec) will solve
          this problem.
      
          Signed-off-by: Lidong Yan <502024330056@smail.nju.edu.cn>
      
       ## mailinfo.c ##
     +@@ mailinfo.c: static int is_format_patch_separator(const char *line, int len)
     + 	return !memcmp(SAMPLE + (cp - line), cp, strlen(SAMPLE) - (cp - line));
     + }
     + 
     +-static struct strbuf *decode_q_segment(const struct strbuf *q_seg, int rfc2047)
     ++static int decode_q_segment(struct strbuf *out, const struct strbuf *q_seg,
     ++			    int rfc2047)
     + {
     + 	const char *in = q_seg->buf;
     + 	int c;
     +-	struct strbuf *out = xmalloc(sizeof(struct strbuf));
     + 	strbuf_init(out, q_seg->len);
     + 
     + 	while ((c = *in++) != 0) {
     +@@ mailinfo.c: static struct strbuf *decode_q_segment(const struct strbuf *q_seg, int rfc2047)
     + 			c = 0x20;
     + 		strbuf_addch(out, c);
     + 	}
     +-	return out;
     ++	return 0;
     + }
     + 
     +-static struct strbuf *decode_b_segment(const struct strbuf *b_seg)
     ++static int decode_b_segment(struct strbuf *out, const struct strbuf *b_seg)
     + {
     + 	/* Decode in..ep, possibly in-place to ot */
     + 	int c, pos = 0, acc = 0;
     + 	const char *in = b_seg->buf;
     +-	struct strbuf *out = xmalloc(sizeof(struct strbuf));
     + 	strbuf_init(out, b_seg->len);
     + 
     + 	while ((c = *in++) != 0) {
     +@@ mailinfo.c: static struct strbuf *decode_b_segment(const struct strbuf *b_seg)
     + 			break;
     + 		}
     + 	}
     +-	return out;
     ++	return 0;
     + }
     + 
     + static int convert_to_utf8(struct mailinfo *mi,
     +@@ mailinfo.c: static int convert_to_utf8(struct mailinfo *mi,
     + static void decode_header(struct mailinfo *mi, struct strbuf *it)
     + {
     + 	char *in, *ep, *cp;
     +-	struct strbuf outbuf = STRBUF_INIT, *dec;
     ++	struct strbuf outbuf = STRBUF_INIT, dec = STRBUF_INIT;
     + 	struct strbuf charset_q = STRBUF_INIT, piecebuf = STRBUF_INIT;
     + 	int found_error = 1; /* pessimism */
     + 
      @@ mailinfo.c: static void decode_header(struct mailinfo *mi, struct strbuf *it)
     - 			dec = decode_q_segment(&piecebuf, 1);
     + 		default:
     + 			goto release_return;
     + 		case 'b':
     +-			dec = decode_b_segment(&piecebuf);
     ++			if ((found_error = decode_b_segment(&dec, &piecebuf))) {
     ++				goto release_return;
     ++			}
     + 			break;
     + 		case 'q':
     +-			dec = decode_q_segment(&piecebuf, 1);
     ++			if ((found_error = decode_q_segment(&dec, &piecebuf, 1))) {
     ++				goto release_return;
     ++			}
       			break;
       		}
      -		if (convert_to_utf8(mi, dec, charset_q.buf))
     -+		if (convert_to_utf8(mi, dec, charset_q.buf)) {
     -+			strbuf_release(dec);
     -+			free(dec);
     ++		if (convert_to_utf8(mi, &dec, charset_q.buf)) {
     ++			strbuf_release(&dec);
       			goto release_return;
      +		}
       
     - 		strbuf_addbuf(&outbuf, dec);
     - 		strbuf_release(dec);
     +-		strbuf_addbuf(&outbuf, dec);
     +-		strbuf_release(dec);
     +-		free(dec);
     ++		strbuf_addbuf(&outbuf, &dec);
     ++		strbuf_release(&dec);
     + 		in = ep + 2;
     + 	}
     + 	strbuf_addstr(&outbuf, in);
     +@@ mailinfo.c: static int is_inbody_header(const struct mailinfo *mi,
     + 
     + static void decode_transfer_encoding(struct mailinfo *mi, struct strbuf *line)
     + {
     +-	struct strbuf *ret;
     ++	struct strbuf ret;
     ++	int found_error = 0;
     + 
     + 	switch (mi->transfer_encoding) {
     + 	case TE_QP:
     +-		ret = decode_q_segment(line, 0);
     ++		found_error = decode_q_segment(&ret, line, 0);
     + 		break;
     + 	case TE_BASE64:
     +-		ret = decode_b_segment(line);
     ++		found_error = decode_b_segment(&ret, line);
     + 		break;
     + 	case TE_DONTCARE:
     + 	default:
     + 		return;
     + 	}
     + 	strbuf_reset(line);
     +-	strbuf_addbuf(line, ret);
     +-	strbuf_release(ret);
     +-	free(ret);
     ++	strbuf_addbuf(line, &ret);
     ++	if (!found_error)
     ++		strbuf_release(&ret);
     + }
     + 
     + static inline int patchbreak(const struct strbuf *line)

 mailinfo.c | 43 ++++++++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 19 deletions(-)