[PATCH v2 3/3] lockdown: Use snprintf in lockdown_read
From: Nikolay Borisov <hidden>
Date: 2025-07-28 11:15:48
Also in:
lkml
Subsystem:
lockdown security module, security subsystem, the rest · Maintainers:
Nicolas Bouchinet, Xiu Jianfeng, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
Since individual features are now locked down separately ensure that if the printing code is change to list them a buffer overrun won't be introduced. As per Serge's recommendation switch from using sprintf to using snprintf and return EINVAL in case longer than 80 char string hasi to be printed. Signed-off-by: Nikolay Borisov <redacted> --- security/lockdown/lockdown.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 412184121279..ed1dde41d7d3 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c@@ -112,11 +112,19 @@ static ssize_t lockdown_read(struct file *filp, char __user *buf, size_t count, if (lockdown_reasons[level]) { const char *label = lockdown_reasons[level]; + int ret = 0; + int write_len = 80-offset; + if (test_bit(level, kernel_locked_down)) - offset += sprintf(temp+offset, "[%s] ", label); + ret = snprintf(temp+offset, write_len, "[%s] ", label); else - offset += sprintf(temp+offset, "%s ", label); + ret = snprintf(temp+offset, write_len, "%s ", label); + + if (ret < 0 || ret >= write_len) + return -ENOMEM; + + offset += ret; } } --
2.34.1