From: Thierry Reding treding@nvidia.com
[ Upstream commit c9f64d1fc101c64ea2be1b2e562b4395127befc9 ]
When dumping the name and NTP servers advertised by DHCP, a blank line is emitted if either of the lists is empty. This can lead to confusing issues such as the blank line getting flagged as warning. This happens because the blank line is the result of pr_cont("\n") and that may see its level corrupted by some other driver concurrently writing to the console.
Fix this by making sure that the terminating newline is only emitted if at least one entry in the lists was printed before.
Reported-by: Jon Hunter jonathanh@nvidia.com Signed-off-by: Thierry Reding treding@nvidia.com Link: https://lore.kernel.org/r/20201110073757.1284594-1-thierry.reding@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/ipconfig.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c index 561f15b5a944e..3cd13e1bc6a70 100644 --- a/net/ipv4/ipconfig.c +++ b/net/ipv4/ipconfig.c @@ -1441,7 +1441,7 @@ static int __init ip_auto_config(void) int retries = CONF_OPEN_RETRIES; #endif int err; - unsigned int i; + unsigned int i, count;
/* Initialise all name servers and NTP servers to NONE (but only if the * "ip=" or "nfsaddrs=" kernel command line parameters weren't decoded, @@ -1575,7 +1575,7 @@ static int __init ip_auto_config(void) if (ic_dev_mtu) pr_cont(", mtu=%d", ic_dev_mtu); /* Name servers (if any): */ - for (i = 0; i < CONF_NAMESERVERS_MAX; i++) { + for (i = 0, count = 0; i < CONF_NAMESERVERS_MAX; i++) { if (ic_nameservers[i] != NONE) { if (i == 0) pr_info(" nameserver%u=%pI4", @@ -1583,12 +1583,14 @@ static int __init ip_auto_config(void) else pr_cont(", nameserver%u=%pI4", i, &ic_nameservers[i]); + + count++; } - if (i + 1 == CONF_NAMESERVERS_MAX) + if ((i + 1 == CONF_NAMESERVERS_MAX) && count > 0) pr_cont("\n"); } /* NTP servers (if any): */ - for (i = 0; i < CONF_NTP_SERVERS_MAX; i++) { + for (i = 0, count = 0; i < CONF_NTP_SERVERS_MAX; i++) { if (ic_ntp_servers[i] != NONE) { if (i == 0) pr_info(" ntpserver%u=%pI4", @@ -1596,8 +1598,10 @@ static int __init ip_auto_config(void) else pr_cont(", ntpserver%u=%pI4", i, &ic_ntp_servers[i]); + + count++; } - if (i + 1 == CONF_NTP_SERVERS_MAX) + if ((i + 1 == CONF_NTP_SERVERS_MAX) && count > 0) pr_cont("\n"); } #endif /* !SILENT */