kernel_optimize_test/include
Vegard Nossum 1147c9cdd0 drm: fix leak of uninitialized data to userspace
...so drm_getunique() is trying to copy some uninitialized data to
userspace. The ECX register contains the number of words that are
left to copy -- so there are 5 * 4 = 20 bytes left. The offset of the
first uninitialized byte (counting from the start of the string) is
also 20 (i.e. 0xf65d2294&((1 << 5)-1) == 20). So somebody tried to
copy 40 bytes when the string was only 19 long.

In drm_set_busid() we have this code:

        dev->unique_len = 40;
        dev->unique = drm_alloc(dev->unique_len + 1, DRM_MEM_DRIVER);
      ...
        len = snprintf(dev->unique, dev->unique_len, pci:%04x:%02x:%02x.%d",

...so it seems that dev->unique is never updated to reflect the
actual length of the string. The remaining bytes (20 in this case)
are random uninitialized bytes that are copied into userspace.

This patch fixes the problem by setting dev->unique_len after the
snprintf().

airlied- I've had to fix this up to store the alloced size so
we have it for drm_free later.

Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: Vegard Nossum <vegardno@thuin.ifi.uio.no>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2008-12-29 17:47:22 +10:00
..
acpi ACPI: don't cond_resched() when irqs_disabled() 2008-12-19 04:38:33 -05:00
asm-arm
asm-frv
asm-generic
asm-h8300
asm-m32r
asm-m68k
asm-mn10300
asm-xtensa
crypto
drm drm: fix leak of uninitialized data to userspace 2008-12-29 17:47:22 +10:00
keys
linux Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-12-18 12:00:46 -08:00
math-emu
media
mtd
net irda: Add irda_skb_cb qdisc related padding 2008-12-17 15:44:58 -08:00
pcmcia
rdma
rxrpc
scsi
sound
trace
video
xen
Kbuild