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[86.9.19.6]) by smtp.gmail.com with ESMTPSA id m9sm3162376wrx.55.2020.02.13.07.06.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Feb 2020 07:06:08 -0800 (PST) From: Daniel Thompson To: Jason Wessel , Daniel Thompson , Douglas Anderson Cc: kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org, patches@linaro.org Subject: [PATCH] kdb: Eliminate strncpy() warnings by replacing with strscpy() Date: Thu, 13 Feb 2020 15:05:53 +0000 Message-Id: <20200213150553.313596-1-daniel.thompson@linaro.org> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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