In preparation for removing the strlcat() API[1], replace its uses in __devlink_compat_running_version().
The function accumulates a variable number of version strings into a fixed buffer, which is what seq_buf is for. The seq_buf is anchored at the end of any existing string in the buffer and each version string is appended with a single seq_buf_printf(). The output is unchanged, including under truncation. Link: https://github.com/KSPP/linux/issues/370 [1] Signed-off-by: Ian Bridges <[email protected]> --- The patch was tested as follows, on top of net-next: - x86_64 allmodconfig and allyesconfig builds of net/devlink/dev.o at W=1 produce no warnings. - A userspace comparison of the old and new construction ran with randomized version lists and buffer contents across all buffer fill levels. The outputs are byte-identical in every case, including on overflow. - The changed path was exercised in a QEMU guest through the ethtool GDRVINFO ioctl against a netdevsim device, before and after the change, with identical fw_version output. net/devlink/dev.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/devlink/dev.c b/net/devlink/dev.c index 57b2b8f03543..0d4301267171 100644 --- a/net/devlink/dev.c +++ b/net/devlink/dev.c @@ -5,6 +5,7 @@ */ #include <linux/device.h> +#include <linux/seq_buf.h> #include <net/genetlink.h> #include <net/sock.h> #include "devl_internal.h" @@ -1188,8 +1189,10 @@ static void __devlink_compat_running_version(struct devlink *devlink, char *buf, size_t len) { struct devlink_info_req req = {}; + size_t used = strnlen(buf, len); const struct nlattr *nlattr; struct sk_buff *msg; + struct seq_buf sb; int rem, err; msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); @@ -1201,6 +1204,8 @@ static void __devlink_compat_running_version(struct devlink *devlink, if (err) goto free_msg; + seq_buf_init(&sb, buf + used, len - used); + nla_for_each_attr_type(nlattr, DEVLINK_ATTR_INFO_VERSION_RUNNING, (void *)msg->data, msg->len, rem) { const struct nlattr *kv; @@ -1208,8 +1213,8 @@ static void __devlink_compat_running_version(struct devlink *devlink, nla_for_each_nested_type(kv, DEVLINK_ATTR_INFO_VERSION_VALUE, nlattr, rem_kv) { - strlcat(buf, nla_data(kv), len); - strlcat(buf, " ", len); + seq_buf_printf(&sb, "%s ", + (const char *)nla_data(kv)); } } free_msg: -- 2.47.3
