Mercurial > vim
changeset 30797:1213e3988168 v9.0.0733
patch 9.0.0733: use of strftime() is not safe
Commit: https://github.com/vim/vim/commit/84d14ccdb50dc9f362066a2c83bfaf331314e5ea
Author: Dominique Pelle <dominique.pelle@gmail.com>
Date: Wed Oct 12 13:30:25 2022 +0100
patch 9.0.0733: use of strftime() is not safe
Problem: Use of strftime() is not safe.
Solution: Check the return value of strftime(). Use a larger buffer and
correctly pass the available space. (Dominique Pell?, closes
#11348)
| author | Bram Moolenaar <Bram@vim.org> |
|---|---|
| date | Wed, 12 Oct 2022 14:45:03 +0200 |
| parents | 454cefb34cfa |
| children | a87c6faa01e3 |
| files | src/time.c src/version.c |
| diffstat | 2 files changed, 22 insertions(+), 11 deletions(-) [+] |
line wrap: on
line diff
--- a/src/time.c +++ b/src/time.c @@ -82,7 +82,7 @@ vim_time(void) char * get_ctime(time_t thetime, int add_newline) { - static char buf[50]; + static char buf[100]; // hopefully enough for every language #ifdef HAVE_STRFTIME struct tm tmval; struct tm *curtime; @@ -90,12 +90,20 @@ get_ctime(time_t thetime, int add_newlin curtime = vim_localtime(&thetime, &tmval); // MSVC returns NULL for an invalid value of seconds. if (curtime == NULL) - vim_strncpy((char_u *)buf, (char_u *)_("(Invalid)"), sizeof(buf) - 1); + vim_strncpy((char_u *)buf, (char_u *)_("(Invalid)"), sizeof(buf) - 2); else { // xgettext:no-c-format - (void)strftime(buf, sizeof(buf) - 1, _("%a %b %d %H:%M:%S %Y"), - curtime); + if (strftime(buf, sizeof(buf) - 2, _("%a %b %d %H:%M:%S %Y"), curtime) + == 0) + { + // Quoting "man strftime": + // > If the length of the result string (including the terminating + // > null byte) would exceed max bytes, then strftime() returns 0, + // > and the contents of the array are undefined. + vim_strncpy((char_u *)buf, (char_u *)_("(Invalid)"), + sizeof(buf) - 2); + } # ifdef MSWIN if (enc_codepage >= 0 && (int)GetACP() != enc_codepage) { @@ -105,7 +113,7 @@ get_ctime(time_t thetime, int add_newlin acp_to_enc((char_u *)buf, (int)strlen(buf), &to_free, &len); if (to_free != NULL) { - STRCPY(buf, to_free); + STRNCPY(buf, to_free, sizeof(buf) - 2); vim_free(to_free); } } @@ -318,10 +326,8 @@ f_strftime(typval_T *argvars, typval_T * convert_setup(&conv, p_enc, enc); if (conv.vc_type != CONV_NONE) p = string_convert(&conv, p, NULL); - if (p != NULL) - (void)strftime((char *)result_buf, sizeof(result_buf), - (char *)p, curtime); - else + if (p == NULL || strftime((char *)result_buf, sizeof(result_buf), + (char *)p, curtime) == 0) result_buf[0] = NUL; if (conv.vc_type != CONV_NONE) @@ -1117,16 +1123,19 @@ add_time(char_u *buf, size_t buflen, tim #ifdef HAVE_STRFTIME struct tm tmval; struct tm *curtime; + int n; if (vim_time() - tt >= 100) { curtime = vim_localtime(&tt, &tmval); if (vim_time() - tt < (60L * 60L * 12L)) // within 12 hours - (void)strftime((char *)buf, buflen, "%H:%M:%S", curtime); + n = strftime((char *)buf, buflen, "%H:%M:%S", curtime); else // longer ago - (void)strftime((char *)buf, buflen, "%Y/%m/%d %H:%M:%S", curtime); + n = strftime((char *)buf, buflen, "%Y/%m/%d %H:%M:%S", curtime); + if (n == 0) + buf[0] = NUL; } else #endif