Re: [PATCH] fix potential infinite loop given large unsigned integer
From: Junio C Hamano <hidden>
Date: 2016-06-15 22:47:12
Subsystem:
the rest · Maintainer:
Linus Torvalds
Possibly related (same subject, not in this thread)
- 2016-06-15 · [PATCH] fix potential infinite loop given large unsigned integer · Ryan Flynn <hidden>
Junio C Hamano [off-list ref] writes:
Ryan Flynn [off-list ref] writes:quoted
given n, tried to find i greater than n via i=1, iterate i *= 10. given n sufficiently close to UINT_MAX this will overflow; which can produce i==0, which results in an infinite loop. iteratively dividing n /= 10 does not have this problem, and though division is slower than multiplication this only runs once per `git format-patch --cover-letter` Signed-off-by: pizza <redacted>Pizza? This is somewhat amusing. - digits_in_number() is called only with opt->total that is "int"; - opt->total is the total number of patches. - the return value is used like this: sprintf(buf, "%0*d", digits_in_number(opt->total), opt->nr); and opt->nr runs from 1 to opt->total; the use of "d" would be already wrong anyway even if you computed digits_in_number() correctly. Perhaps we should get rid of this function altogether?
Or perhaps something stupid like this... builtin-log.c | 6 +++++- log-tree.c | 12 +----------- revision.h | 2 +- 3 files changed, 7 insertions(+), 13 deletions(-)
diff --git a/builtin-log.c b/builtin-log.c
index 3817bf1..321e8f5 100644
--- a/builtin-log.c
+++ b/builtin-log.c@@ -1096,8 +1096,12 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix) total = nr; if (!keep_subject && auto_number && total > 1) numbered = 1; - if (numbered) + if (numbered) { + static char num_buf[64]; rev.total = total + start_number - 1; + sprintf(num_buf, "%d", rev.total); + rev.num_width = strlen(num_buf); + } if (in_reply_to || thread || cover_letter) rev.ref_message_ids = xcalloc(1, sizeof(struct string_list)); if (in_reply_to) {
diff --git a/log-tree.c b/log-tree.c
index 6f73c17..0d32a6c 100644
--- a/log-tree.c
+++ b/log-tree.c@@ -158,16 +158,6 @@ static void append_signoff(struct strbuf *sb, const char *signoff) strbuf_addch(sb, '\n'); } -static unsigned int digits_in_number(unsigned int number) -{ - unsigned int i = 10, result = 1; - while (i <= number) { - i *= 10; - result++; - } - return result; -} - static int has_non_ascii(const char *s) { int ch;
@@ -212,7 +202,7 @@ void log_write_email_headers(struct rev_info *opt, struct commit *commit, snprintf(buffer, sizeof(buffer), "Subject: [%s %0*d/%d] ", opt->subject_prefix, - digits_in_number(opt->total), + opt->num_width, opt->nr, opt->total); subject = buffer; } else if (opt->total == 0 && opt->subject_prefix && *opt->subject_prefix) {
diff --git a/revision.h b/revision.h
index fb74492..21e4d9d 100644
--- a/revision.h
+++ b/revision.h@@ -84,7 +84,7 @@ struct rev_info { unsigned int abbrev; enum cmit_fmt commit_format; struct log_info *loginfo; - int nr, total; + int nr, total, num_width; const char *mime_boundary; const char *patch_suffix; int numbered_files;