Re: [PATCH 27/28] drm/xe/pf: Convert strlcat() to seq_buf in control_read()
From: Kees Cook <kees@kernel.org>
Date: 2026-09-15 18:25:23
Also in:
dri-devel, intel-wired-lan, intel-xe, linux-devicetree, linux-edac, linux-gpio, linux-hardening, linux-media, linux-mips, linux-nfs, linux-samsung-soc, linux-scsi, linux-sound, linux-wireless, lkml, loongarch, netdev
On Tue, Sep 15, 2026 at 08:18:44AM +0000, Bill Wendling wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c index 0f242db775e1..5db7fc067c4d 100644 --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_debugfs.c@@ -4,6 +4,7 @@ */ #include <linux/debugfs.h> +#include <linux/seq_buf.h> #include <drm/drm_print.h> #include <drm/drm_debugfs.h>@@ -663,15 +664,15 @@ static ssize_t control_write(struct file *file, const char __user *buf, size_t c static ssize_t control_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { char help[128]; + struct seq_buf s; size_t n; - help[0] = '\0'; + seq_buf_init(&s, help, sizeof(help)); for (n = 0; n < ARRAY_SIZE(control_cmds); n++) { - strlcat(help, control_cmds[n].cmd, sizeof(help)); - strlcat(help, "\n", sizeof(help)); + seq_buf_printf(&s, "%s\n", control_cmds[n].cmd); }
Yay seq_buf! I would tweak the 3 init stack variable lines into just using the single DECLARE_SEQ_BUF: DECLARE_SEQ_BUF(s, 128);
- return simple_read_from_buffer(buf, count, ppos, help, strlen(help)); + return simple_read_from_buffer(buf, count, ppos, help, seq_buf_used(&s));
seq_buf_used() isn't correct in the case of full-buffer use. e.g. if the help buffer ends up filled with 127 chars and a NUL terminator, seq_buf_used() returns 128, but you want 127 here. Using strlen() ends up being redundant, though. I think we need to add seq_buf_strlen() which handles the same logic that seq_buf_str() does. -Kees -- Kees Cook