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patch "vt: keyboard, simplify vt_kdgkbsent" added to tty-linus

PATCH [email protected] 1 participant 1 message Oct 29, 2020

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This is a note to let you know that I've just added the patch titled

vt: keyboard, simplify vt_kdgkbsent

to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 6ca03f90527e499dd5e32d6522909e2ad390896b Mon Sep 17 00:00:00 2001
From: Jiri Slaby <[email protected]>
Date: Mon, 19 Oct 2020 10:55:16 +0200
Subject: vt: keyboard, simplify vt_kdgkbsent

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.

Cc <[email protected]>
Signed-off-by Jiri Slaby <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/tty/vt/keyboard.c | 28 +++++++++-------------------
 1 file changed, 9 insertions(+), 19 deletions(-)
drivers/tty/vt/keyboard.c +9 -19
index 0db53b5b3acf..7bfa95c3252c 100644
@@ -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;
Signature · 1 line
2.29.1