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CVE-2014-7843 aarch64: copying from /dev/zero causes local DoS (rhbz 1163744 1163745)

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This commit is contained in:
Josh Boyer 2014-11-13 08:30:23 -05:00
parent d21f4c390b
commit d31dd42af0
2 changed files with 68 additions and 0 deletions
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59
arm64-__clear_user-handle-exceptions-on-strb.patch Normal file
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@ -0,0 +1,59 @@
From 98e676789aa06582cb0d0f7758e77864b38c12a7 Mon Sep 17 00:00:00 2001
From: Kyle McMartin <kyle@redhat.com>
Date: Wed, 12 Nov 2014 16:07:44 -0500
Subject: [PATCH] arm64: __clear_user: handle exceptions on strb
ARM64 currently doesn't fix up faults on the single-byte (strb) case of
__clear_user... which means that we can cause a nasty kernel panic as an
ordinary user with any multiple PAGE_SIZE+1 read from /dev/zero.
i.e.: dd if=/dev/zero of=foo ibs=1 count=1 (or ibs=65537, etc.)
This is a pretty obscure bug in the general case since we'll only
__do_kernel_fault (since there's no extable entry for pc) if the
mmap_sem is contended. However, with CONFIG_DEBUG_VM enabled, we'll
always fault.
if (!down_read_trylock(&mm->mmap_sem)) {
if (!user_mode(regs) && !search_exception_tables(regs->pc))
goto no_context;
retry:
down_read(&mm->mmap_sem);
} else {
/*
* The above down_read_trylock() might have succeeded in
* which
* case, we'll have missed the might_sleep() from
* down_read().
*/
might_sleep();
#ifdef CONFIG_DEBUG_VM
if (!user_mode(regs) && !search_exception_tables(regs->pc))
goto no_context;
#endif
}
Fix that by adding an extable entry for the strb instruction, since it
touches user memory, similar to the other stores in __clear_user.
Signed-off-by: Kyle McMartin <kyle@redhat.com>
Cc: stable@vger.kernel.org
---
arch/arm64/lib/clear_user.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
index 6e0ed93d51fe..c17967fdf5f6 100644
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -46,7 +46,7 @@ USER(9f, strh wzr, [x0], #2 )
sub x1, x1, #2
4: adds x1, x1, #1
b.mi 5f
- strb wzr, [x0]
+USER(9f, strb wzr, [x0] )
5: mov x0, #0
ret
ENDPROC(__clear_user)
--
1.9.3

9
kernel.spec
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@ -622,6 +622,9 @@ Patch26066: ahci-disable-MSI-instead-of-NCQ-on-Samsung-pci-e-SSD.patch
#CVE-2014-7841 rhbz 1163087 1163095
Patch26067: net-sctp-fix-NULL-pointer-dereference-in-af-from_add.patch
#CVE-2014-7843 rhbz 1163744 1163745
Patch26069: arm64-__clear_user-handle-exceptions-on-strb.patch
# git clone ssh://git.fedorahosted.org/git/kernel-arm64.git, git diff master...devel
Patch30000: kernel-arm64.patch
@ -1353,6 +1356,9 @@ ApplyPatch ahci-disable-MSI-instead-of-NCQ-on-Samsung-pci-e-SSD.patch
#CVE-2014-7841 rhbz 1163087 1163095
ApplyPatch net-sctp-fix-NULL-pointer-dereference-in-af-from_add.patch
#CVE-2014-7843 rhbz 1163744 1163745
ApplyPatch arm64-__clear_user-handle-exceptions-on-strb.patch
%if 0%{?aarch64patches}
ApplyPatch kernel-arm64.patch
%ifnarch aarch64 # this is stupid, but i want to notice before secondary koji does.
@ -2221,6 +2227,9 @@ fi
# ||----w |
# || ||
%changelog
* Thu Nov 13 2014 Josh Boyer <jwboyer@fedoraproject.org>
- CVE-2014-7843 aarch64: copying from /dev/zero causes local DoS (rhbz 1163744 1163745)
* Thu Nov 13 2014 Josh Boyer <jwboyer@fedoraproject.org> - 3.18.0-0.rc4.git1.1
- Linux v3.18-rc4-52-g04689e749b7e
- Reenable debugging options.