diff options
| author | Azeem Shaikh <azeems@google.com> | 2023-09-19 19:21:56 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-10-03 14:36:09 +0200 |
| commit | 95e8e7eebab58ec8f6c978242a6d143ba238a69e (patch) | |
| tree | 54f82ca331524ef9a3109209f4044c464f1bf34c /drivers/tty/vt/keyboard.c | |
| parent | 29bff582b74ed0bdb7e6986482ad9e6799ea4d2f (diff) | |
vt: Replace strlcpy with strscpy
strlcpy() reads the entire source buffer first and returns the size of
the source string, not the destination string, which can be accidentally
misused [1].
The copy_to_user() call uses @len returned from strlcpy() directly
without checking its value. This could potentially lead to read
overflow. There is no existing bug since @len is always guaranteed to be
greater than hardcoded strings in @func_table[kb_func]. But as written
it is very fragile and specifically uses a strlcpy() result without sanity
checking and using it to copy to userspace.
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89
Signed-off-by: Azeem Shaikh <azeems@google.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230919192156.121503-1-azeems@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/vt/keyboard.c')
| -rw-r--r-- | drivers/tty/vt/keyboard.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index 358f216c6cd6..6e8eeffbdae4 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -2079,12 +2079,15 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) return -ENOMEM; spin_lock_irqsave(&func_buf_lock, flags); - len = strlcpy(kbs, func_table[kb_func] ? : "", len); + len = strscpy(kbs, func_table[kb_func] ? : "", len); spin_unlock_irqrestore(&func_buf_lock, flags); + if (len < 0) { + ret = -ENOSPC; + break; + } ret = copy_to_user(user_kdgkb->kb_string, kbs, len + 1) ? -EFAULT : 0; - break; } case KDSKBSENT: |