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kdb: Eliminate strncpy() warnings by replacing with strscpy()

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Currently the code to manage the kdb history buffer uses strncpy() to
copy strings to/and from the history and exhibits the classic "but
nobody ever told me that strncpy() doesn't always terminate strings"
bug. Modern gcc compilers recognise this bug and issue a warning.

In reality these calls will only abridge the copied string if kdb_read()
has *already* overflowed the command buffer. Thus the use of counted
copies here is only used to reduce the secondary effects of a bug
elsewhere in the code.

Therefore transitioning these calls into strscpy() (without checking
the return code) is appropriate.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
This commit is contained in:
Daniel Thompson 2020-02-13 09:57:24 +00:00
parent 7111951b8d
commit d228bee820
1 changed files with 4 additions and 4 deletions
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8
kernel/debug/kdb/kdb_main.c
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@ -1102,12 +1102,12 @@ static int handle_ctrl_cmd(char *cmd)
case CTRL_P: case CTRL_P:
if (cmdptr != cmd_tail) if (cmdptr != cmd_tail)
cmdptr = (cmdptr-1) % KDB_CMD_HISTORY_COUNT; cmdptr = (cmdptr-1) % KDB_CMD_HISTORY_COUNT;
strncpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN); strscpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN);
return 1; return 1;
case CTRL_N: case CTRL_N:
if (cmdptr != cmd_head) if (cmdptr != cmd_head)
cmdptr = (cmdptr+1) % KDB_CMD_HISTORY_COUNT; cmdptr = (cmdptr+1) % KDB_CMD_HISTORY_COUNT;
strncpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN); strscpy(cmd_cur, cmd_hist[cmdptr], CMD_BUFLEN);
return 1; return 1;
} }
return 0; return 0;
@ -1314,7 +1314,7 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
if (*cmdbuf != '\n') { if (*cmdbuf != '\n') {
if (*cmdbuf < 32) { if (*cmdbuf < 32) {
if (cmdptr == cmd_head) { if (cmdptr == cmd_head) {
strncpy(cmd_hist[cmd_head], cmd_cur, strscpy(cmd_hist[cmd_head], cmd_cur,
CMD_BUFLEN); CMD_BUFLEN);
*(cmd_hist[cmd_head] + *(cmd_hist[cmd_head] +
strlen(cmd_hist[cmd_head])-1) = '\0'; strlen(cmd_hist[cmd_head])-1) = '\0';
@ -1324,7 +1324,7 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
cmdbuf = cmd_cur; cmdbuf = cmd_cur;
goto do_full_getstr; goto do_full_getstr;
} else { } else {
strncpy(cmd_hist[cmd_head], cmd_cur, strscpy(cmd_hist[cmd_head], cmd_cur,
CMD_BUFLEN); CMD_BUFLEN);
} }