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| author | Alexander Potapenko <glider@google.com> | 2018-06-14 12:23:09 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-07-11 16:26:42 +0200 |
| commit | 3bf351b89186181f9869612bd502ff115209abf0 (patch) | |
| tree | c7919b363e5b72631a008bb2007152669a0cbe49 | |
| parent | 06bef9eebec3aa9543ac6196d983632d5fafe6f0 (diff) | |
| download | linux-stable-3bf351b89186181f9869612bd502ff115209abf0.tar.gz linux-stable-3bf351b89186181f9869612bd502ff115209abf0.tar.bz2 linux-stable-3bf351b89186181f9869612bd502ff115209abf0.zip | |
vt: prevent leaking uninitialized data to userspace via /dev/vcs*
commit 21eff69aaaa0e766ca0ce445b477698dc6a9f55a upstream.
KMSAN reported an infoleak when reading from /dev/vcs*:
BUG: KMSAN: kernel-infoleak in vcs_read+0x18ba/0x1cc0
Call Trace:
...
kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1253
copy_to_user ./include/linux/uaccess.h:184
vcs_read+0x18ba/0x1cc0 drivers/tty/vt/vc_screen.c:352
__vfs_read+0x1b2/0x9d0 fs/read_write.c:416
vfs_read+0x36c/0x6b0 fs/read_write.c:452
...
Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279
kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189
kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315
__kmalloc+0x13a/0x350 mm/slub.c:3818
kmalloc ./include/linux/slab.h:517
vc_allocate+0x438/0x800 drivers/tty/vt/vt.c:787
con_install+0x8c/0x640 drivers/tty/vt/vt.c:2880
tty_driver_install_tty drivers/tty/tty_io.c:1224
tty_init_dev+0x1b5/0x1020 drivers/tty/tty_io.c:1324
tty_open_by_driver drivers/tty/tty_io.c:1959
tty_open+0x17b4/0x2ed0 drivers/tty/tty_io.c:2007
chrdev_open+0xc25/0xd90 fs/char_dev.c:417
do_dentry_open+0xccc/0x1440 fs/open.c:794
vfs_open+0x1b6/0x2f0 fs/open.c:908
...
Bytes 0-79 of 240 are uninitialized
Consistently allocating |vc_screenbuf| with kzalloc() fixes the problem
Reported-by: syzbot+17a8efdf800000@syzkaller.appspotmail.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/vt/vt.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 9e1ac58e269e..9d3e413f48c6 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -785,7 +785,7 @@ int vc_allocate(unsigned int currcons) /* return 0 on success */ if (!*vc->vc_uni_pagedir_loc) con_set_default_unimap(vc); - vc->vc_screenbuf = kmalloc(vc->vc_screenbuf_size, GFP_KERNEL); + vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_KERNEL); if (!vc->vc_screenbuf) goto err_free; @@ -872,7 +872,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc, if (new_screen_size > (4 << 20)) return -EINVAL; - newscreen = kmalloc(new_screen_size, GFP_USER); + newscreen = kzalloc(new_screen_size, GFP_USER); if (!newscreen) return -ENOMEM; |