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Subject[PATCH] kdb: Eliminate strncpy() warnings by replacing with strscpy()
Date
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>
---
kernel/debug/kdb/kdb_main.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index ba12e9f4661e..a4641be4123c 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1102,12 +1102,12 @@ static int handle_ctrl_cmd(char *cmd)
case CTRL_P:
if (cmdptr != cmd_tail)
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;
case CTRL_N:
if (cmdptr != cmd_head)
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 0;
@@ -1314,7 +1314,7 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
if (*cmdbuf != '\n') {
if (*cmdbuf < 32) {
if (cmdptr == cmd_head) {
- strncpy(cmd_hist[cmd_head], cmd_cur,
+ strscpy(cmd_hist[cmd_head], cmd_cur,
CMD_BUFLEN);
*(cmd_hist[cmd_head] +
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;
goto do_full_getstr;
} else {
- strncpy(cmd_hist[cmd_head], cmd_cur,
+ strscpy(cmd_hist[cmd_head], cmd_cur,
CMD_BUFLEN);
}

base-commit: bb6d3fb354c5ee8d6bde2d576eb7220ea09862b9
--
2.23.0

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