[PATCH] hamradio: Fix wrong assignment of 'bbc->cfg.loopback'

[PATCH] hamradio: Fix wrong assignment of 'bbc->cfg.loopback'

[Meng Tang]

In file hamradio/baycom_epp.c, the baycom_setmode interface, there
is a problem with improper use of strstr.

Suppose that when modestr="noloopback", both conditions which are
'strstr(modestr,"noloopback")' and 'strstr(modestr,"loopback")'
will be true(not NULL), this lead the bc->cfg.loopback variable
will be first assigned to 0, and then reassigned to 1.

This will cause 'bc->cfg.loopback = 0' will never take effect. That
obviously violates the logic of the code, so adjust the order of
their execution to solve the problem.

Signed-off-by: Meng Tang <tangmeng@uniontech.com>
---
 drivers/net/hamradio/baycom_epp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c
index a03d0b474641..36e6de42ae77 100644
--- a/drivers/net/hamradio/baycom_epp.c
+++ b/drivers/net/hamradio/baycom_epp.c
@@ -982,10 +982,10 @@ static int baycom_setmode(struct baycom_state *bc, const char *modestr)
 		bc->cfg.extmodem = 0;
 	if (strstr(modestr,"extmodem"))
 		bc->cfg.extmodem = 1;
-	if (strstr(modestr,"noloopback"))
-		bc->cfg.loopback = 0;
 	if (strstr(modestr,"loopback"))
 		bc->cfg.loopback = 1;
+	if (strstr(modestr, "noloopback"))
+		bc->cfg.loopback = 0;
 	if ((cp = strstr(modestr,"fclk="))) {
 		bc->cfg.fclk = simple_strtoul(cp+5, NULL, 0);
 		if (bc->cfg.fclk < 1000000)
-- 
2.20.1

Re: [PATCH] hamradio: Fix wrong assignment of 'bbc->cfg.loopback'

[Dan Carpenter]

On Tue, Mar 15, 2022 at 03:48:51PM +0800, Meng Tang wrote:
> In file hamradio/baycom_epp.c, the baycom_setmode interface, there
> is a problem with improper use of strstr.
> 
> Suppose that when modestr="noloopback", both conditions which are
> 'strstr(modestr,"noloopback")' and 'strstr(modestr,"loopback")'
> will be true(not NULL), this lead the bc->cfg.loopback variable
> will be first assigned to 0, and then reassigned to 1.
> 
> This will cause 'bc->cfg.loopback = 0' will never take effect. That
> obviously violates the logic of the code, so adjust the order of
> their execution to solve the problem.
> 
> Signed-off-by: Meng Tang <tangmeng@uniontech.com>

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>

This bug predates git.  :P  Did you find it by testing or reviewing the
code?

regards,
dan carpenter

Re: [PATCH] hamradio: Fix wrong assignment of 'bbc->cfg.loopback'

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 15 Mar 2022 15:48:51 +0800 you wrote:
> In file hamradio/baycom_epp.c, the baycom_setmode interface, there
> is a problem with improper use of strstr.
> 
> Suppose that when modestr="noloopback", both conditions which are
> 'strstr(modestr,"noloopback")' and 'strstr(modestr,"loopback")'
> will be true(not NULL), this lead the bc->cfg.loopback variable
> will be first assigned to 0, and then reassigned to 1.
> 
> [...]

Here is the summary with links:
  - hamradio: Fix wrong assignment of 'bbc->cfg.loopback'
    https://git.kernel.org/netdev/net-next/c/a8df216630fe

You are awesome, thank you!
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