diff options
author | Jiri Slaby <jslaby@suse.cz> | 2020-10-29 12:32:16 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-11-04 16:43:38 +0100 |
commit | 07edff9265204e15c9fc8d07cc69e38c4c484e15 (patch) | |
tree | 41bac874491adee454224fd78c666d8d7564d58e /drivers/tty/vt | |
parent | 9788c950ed4ad2020a7f2e8231abaf77e49d871a (diff) | |
download | linux-07edff9265204e15c9fc8d07cc69e38c4c484e15.tar.bz2 |
vt: keyboard, reorder user buffer handling in vt_do_kdgkb_ioctl
KDGKBSENT (the getter) needs only 'user_kdgkb->kb_func' from the
userspace, i.e. the index. Then it needs a buffer for a local copy of
'kb_string'.
KDSKBSENT (the setter) needs a copy up to the length of
'user_kdgkb->kb_string'.
That means, we obtain the index before the switch-case and use it in
both paths and:
1) allocate full space in the getter case, and
2) copy the string only in the setter case. We do it by strndup_user
helper now which was not available when this function was written.
Given we copy the two members of 'struct kbsentry' separately, we no
longer need a local definition. Hence we need to change all the sizeofs
here too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-11-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/vt')
-rw-r--r-- | drivers/tty/vt/keyboard.c | 42 |
1 files changed, 20 insertions, 22 deletions
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index 55014f57a3de..81afe0438b34 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -2021,7 +2021,7 @@ int vt_do_kdsk_ioctl(int cmd, struct kbentry __user *user_kbe, int perm, /* FIXME: This one needs untangling */ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) { - struct kbsentry *kbs; + char *kbs; u_char *q; int sz, fnw_sz; int delta; @@ -2034,39 +2034,37 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) if (!capable(CAP_SYS_TTY_CONFIG)) perm = 0; - kbs = kmalloc(sizeof(*kbs), GFP_KERNEL); - if (!kbs) { - ret = -ENOMEM; - goto reterr; - } + if (get_user(kb_func, &user_kdgkb->kb_func)) + return -EFAULT; - /* we mostly copy too much here (512bytes), but who cares ;) */ - if (copy_from_user(kbs, user_kdgkb, sizeof(struct kbsentry))) { - ret = -EFAULT; - goto reterr; - } - kbs->kb_string[sizeof(kbs->kb_string)-1] = '\0'; - kb_func = array_index_nospec(kbs->kb_func, MAX_NR_FUNC); + kb_func = array_index_nospec(kb_func, MAX_NR_FUNC); switch (cmd) { case KDGKBSENT: { /* size should have been a struct member */ ssize_t len = sizeof(user_kdgkb->kb_string); + kbs = kmalloc(len, GFP_KERNEL); + if (!kbs) + return -ENOMEM; + spin_lock_irqsave(&func_buf_lock, flags); - len = strlcpy(kbs->kb_string, func_table[kb_func] ? : "", len); + len = strlcpy(kbs, func_table[kb_func] ? : "", len); spin_unlock_irqrestore(&func_buf_lock, flags); - ret = copy_to_user(user_kdgkb->kb_string, kbs->kb_string, - len + 1) ? -EFAULT : 0; + ret = copy_to_user(user_kdgkb->kb_string, kbs, len + 1) ? + -EFAULT : 0; goto reterr; } case KDSKBSENT: - if (!perm) { - ret = -EPERM; - goto reterr; - } + if (!perm) + return -EPERM; + + kbs = strndup_user(user_kdgkb->kb_string, + sizeof(user_kdgkb->kb_string)); + if (IS_ERR(kbs)) + return PTR_ERR(kbs); fnw = NULL; fnw_sz = 0; @@ -2084,7 +2082,7 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) else fj = first_free; /* buffer usage increase by new entry */ - delta = (q ? -strlen(q) : 1) + strlen(kbs->kb_string); + delta = (q ? -strlen(q) : 1) + strlen(kbs); if (delta <= funcbufleft) { /* it fits in current buf */ if (j < MAX_NR_FUNC) { @@ -2136,7 +2134,7 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) funcbufsize = sz; } /* finally insert item itself */ - strcpy(func_table[kb_func], kbs->kb_string); + strcpy(func_table[kb_func], kbs); spin_unlock_irqrestore(&func_buf_lock, flags); break; } |