Enabling DEBUG_STRICT_USER_COPY_CHECKS causes the following warning:

In file included from arch/x86/include/asm/uaccess.h:573,
                 from kernel/kprobes.c:55:
In function 'copy_from_user',
    inlined from 'write_enabled_file_bool' at
    kernel/kprobes.c:2191:
arch/x86/include/asm/uaccess_64.h:65:
warning: call to 'copy_from_user_overflow' declared with
attribute warning: copy_from_user() buffer size is not provably
correct

presumably due to buf_size being signed causing GCC to fail to see that
buf_size can't become negative.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 184d8987489d32c974b0f80dcab8fba992322e0b..d3466d09a7ca790048517ce5d712214873470be8 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2198,7 +2198,7 @@ static ssize_t write_enabled_file_bool(struct file *file,
               const char __user *user_buf, size_t count, loff_t *ppos)
 {
        char buf[32];
-       int buf_size;
+       size_t buf_size;
 
        buf_size = min(count, (sizeof(buf)-1));
        if (copy_from_user(buf, user_buf, buf_size))