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top: be more careful with memcpy length specifications

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Using 'mempcpy' was a mistake where plain old 'memcpy'
was appropriate. More importantly, the careless length
specified resulted in a SEGV under some circumstances.

[ namely, it occurred under a multi-threaded top and ]
[ the top program itself as focus + CtrlN 'environ'. ]

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner 2022-05-17 00:00:00 -05:00 committed by Craig Small
parent 73b4f1134f
commit c00d09edf1
1 changed files with 10 additions and 3 deletions
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13
top/top.c
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@ -4933,8 +4933,12 @@ static int bot_focus_str (const char *hdr, const char *str) {
int n, x;
if (str) {
// we're a little careless with overhead here (it's a one time cost)
memset(Bot_buf, '\0', sizeof(Bot_buf));
n = strlen(str);
if (n >= sizeof(Bot_buf)) n = sizeof(Bot_buf) - 1;
if (!*str || !strcmp(str, "-")) strcpy(Bot_buf, "n/a");
else memccpy(Bot_buf, str, '\0', sizeof(Bot_buf) - 1);
else memccpy(Bot_buf, str, '\0', n);
Bot_rsvd = 1 + BOT_RSVD + (strlen(Bot_buf) / Screen_cols);
if (Bot_rsvd > maxRSVD) Bot_rsvd = maxRSVD;
// caller itself may have used fmtmk, so we'll old school it ...
@ -4975,8 +4979,11 @@ static int bot_focus_strv (const char *hdr, const char **strv) {
int i, n, x;
if (strv) {
// we won't worry about picking up some trailing garbage ...
mempcpy(Bot_buf, strv[0], sizeof(Bot_buf));
// we're a little careless with overhead here (it's a one time cost)
memset(Bot_buf, '\0', sizeof(Bot_buf));
n = (void*)&strv[0] - (void*)strv[0];
if (n >= sizeof(Bot_buf)) n = sizeof(Bot_buf) - 1;
memcpy(Bot_buf, strv[0], n);
for (nsav= 0, p = Bot_buf; strv[nsav] != NULL; nsav++) {
p += strlen(strv[nsav]) + 1;
if ((p - Bot_buf) >= sizeof(Bot_buf))