Use 'strlen' of the string, add one for NUL terminator and simply do 'copy_to_user' instead of the explicit 'for' loop. This makes the KDGKBSENT case more compact.
The only thing we need to take care about is NULL 'func_table[i]'. Use an empty string in that case.
The original check for overflow could never trigger as the func_buf strings are always shorter or equal to 'struct kbsentry's.
Signed-off-by: Jiri Slaby jslaby@suse.cz Cc: stable@vger.kernel.org ---
[v2] Removed the need for "reorder user buffer handling in vt_do_kdgkb_ioctl" patch.
drivers/tty/vt/keyboard.c | 28 +++++++++------------------- 1 file changed, 9 insertions(+), 19 deletions(-)
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index 0db53b5b3acf..7bfa95c3252c 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -1995,9 +1995,7 @@ int vt_do_kdsk_ioctl(int cmd, struct kbentry __user *user_kbe, int perm, int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) { struct kbsentry *kbs; - char *p; u_char *q; - u_char __user *up; int sz, fnw_sz; int delta; char *first_free, *fj, *fnw; @@ -2023,23 +2021,15 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) i = array_index_nospec(kbs->kb_func, MAX_NR_FUNC);
switch (cmd) { - case KDGKBSENT: - sz = sizeof(kbs->kb_string) - 1; /* sz should have been - a struct member */ - up = user_kdgkb->kb_string; - p = func_table[i]; - if(p) - for ( ; *p && sz; p++, sz--) - if (put_user(*p, up++)) { - ret = -EFAULT; - goto reterr; - } - if (put_user('\0', up)) { - ret = -EFAULT; - goto reterr; - } - kfree(kbs); - return ((p && *p) ? -EOVERFLOW : 0); + case KDGKBSENT: { + /* size should have been a struct member */ + unsigned char *from = func_table[i] ? : ""; + + ret = copy_to_user(user_kdgkb->kb_string, from, + strlen(from) + 1) ? -EFAULT : 0; + + goto reterr; + } case KDSKBSENT: if (!perm) { ret = -EPERM;