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Vitaly Kuznetsov 55f1ea1521 efi: Fix for_each_efi_memory_desc_in_map() for empty memmaps 
Commit:

  78ce248faa ("efi: Iterate over efi.memmap in for_each_efi_memory_desc()")

introduced a regression for systems booted with the 'noefi' kernel option.

In particular, I observed an early kernel hang in efi_find_mirror()'s
for_each_efi_memory_desc() call. As we don't have efi memmap on this
system we enter this iterator with the following parameters:

  efi.memmap.map = 0, efi.memmap.map_end = 0, efi.memmap.desc_size = 28

... then for_each_efi_memory_desc_in_map() does the following comparison:

  (md) <= (efi_memory_desc_t *)((m)->map_end - (m)->desc_size);

... where md = 0, (m)->map_end = 0 and (m)->desc_size = 28 but when we subtract
something from a NULL pointer wrap around happens and we end up returning
invalid pointer and crash.

Fix it by using the correct pointer arithmetics.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 78ce248faa ("efi: Iterate over efi.memmap in for_each_efi_memory_desc()")
Link: http://lkml.kernel.org/r/1464690224-4503-2-git-send-email-matt@codeblueprint.co.uk
[ Made the changelog more readable. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-03 09:57:35 +02:00
..
acpi libnvdimm for 4.7 2016-05-23 11:18:01 -07:00
asm-generic Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-05-25 17:11:43 -07:00
clocksource clocksource: arm_arch_timer: Remove arch_timer_get_timecounter 2016-05-03 12:54:21 +02:00
crypto Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-05-19 09:21:36 -07:00
drm Merge tag 'drm-intel-next-fixes-2016-05-25' of git://anongit.freedesktop.org/drm-intel into drm-next 2016-05-27 16:08:38 +10:00
dt-bindings Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2016-05-26 09:23:43 -07:00
keys
kvm KVM: arm/arm64: vgic-new: implement mapped IRQ handling 2016-05-20 15:40:09 +02:00
linux efi: Fix for_each_efi_memory_desc_in_map() for empty memmaps 2016-06-03 09:57:35 +02:00
math-emu
media [media] media: rc: reduce size of struct ir_raw_event 2016-05-07 10:34:17 -03:00
memory
misc cxl: Add kernel API to allow a context to operate with relocate disabled 2016-05-11 21:54:10 +10:00
net ipv6: hide ip6_encap_hlen/ip6_tnl_encap definitions 2016-05-29 22:24:21 -07:00
pcmcia
ras
rdma IB/core: Make device counter infrastructure dynamic 2016-05-26 12:52:51 -04:00
rxrpc
scsi Merge branch '4.7/scsi-queue' of git://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi into for-4.7-zac 2016-05-09 12:34:39 -04:00
soc ARC updates for 4.7-rc1 2016-05-19 09:46:18 -07:00
sound ASoC: Updates for v4.7 2016-05-16 14:59:00 +02:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2016-05-28 12:04:17 -07:00
trace - move kvm_stat tool from QEMU repo into tools/kvm/kvm_stat 2016-05-27 13:41:54 -07:00
uapi Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-05-31 22:28:28 -07:00
video imx-drm probing fix 2016-05-25 12:36:20 +10:00
xen
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