| Message ID | 20241017152422.487406-2-atenart@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d631094e4d20d136f159c6e0f723b7aecbc12d2f |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: sysctl: allow dump_cpumask to handle higher numbers of CPUs | expand |
On Thu, Oct 17, 2024 at 05:24:17PM +0200, Antoine Tenart wrote: > Before adding a new line at the end of the temporary buffer in > dump_cpumask, a length check is performed to ensure there is space for > it. > > len = min(sizeof(kbuf) - 1, *lenp); > len = scnprintf(kbuf, len, ...); > if (len < *lenp) > kbuf[len++] = '\n'; > > Note that the check is currently logically wrong, the written length is > compared against the output buffer, not the temporary one. However this > has no consequence as this is always true, even if fixed: scnprintf > includes a null char at the end of the buffer but the returned length do > not include it and there is always space for overriding it with a > newline. > > Remove the condition. > > Signed-off-by: Antoine Tenart <atenart@kernel.org> Thanks for separating out this and patch 2/3. It makes it much easier to reason with these changes. Reviewed-by: Simon Horman <horms@kernel.org>
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index b60fac380cec..e7c0121dfaa1 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -69,8 +69,10 @@ static void dump_cpumask(void *buffer, size_t *lenp, loff_t *ppos, return; } - if (len < *lenp) - kbuf[len++] = '\n'; + /* scnprintf writes a trailing null char not counted in the returned + * length, override it with a newline. + */ + kbuf[len++] = '\n'; memcpy(buffer, kbuf, len); *lenp = len; *ppos += len;
Before adding a new line at the end of the temporary buffer in dump_cpumask, a length check is performed to ensure there is space for it. len = min(sizeof(kbuf) - 1, *lenp); len = scnprintf(kbuf, len, ...); if (len < *lenp) kbuf[len++] = '\n'; Note that the check is currently logically wrong, the written length is compared against the output buffer, not the temporary one. However this has no consequence as this is always true, even if fixed: scnprintf includes a null char at the end of the buffer but the returned length do not include it and there is always space for overriding it with a newline. Remove the condition. Signed-off-by: Antoine Tenart <atenart@kernel.org> --- net/core/sysctl_net_core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)