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authorAlexander Potapenko <glider@google.com>2018-06-14 12:23:09 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-06-28 21:34:39 +0900
commit21eff69aaaa0e766ca0ce445b477698dc6a9f55a (patch)
treedf798041ef986a7e5cf8883369160c3d09cc2146 /drivers/tty/vt
parentbc6cf3669d22371f573ab0305b3abf13887c0786 (diff)
vt: prevent leaking uninitialized data to userspace via /dev/vcs*
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>
Diffstat (limited to 'drivers/tty/vt')
-rw-r--r--drivers/tty/vt/vt.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 1eb1a376a041..15eb6c829d39 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -784,7 +784,7 @@ 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;
@@ -871,7 +871,7 @@ 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;