# git rev-parse -q --verify 61a8426c92ba30d403a1f072e29d713184539cc1^{commit}
61a8426c92ba30d403a1f072e29d713184539cc1
already have revision, skipping fetch
# git checkout -q -f -B kisskb 61a8426c92ba30d403a1f072e29d713184539cc1
# git clean -qxdf
# < git log -1
# commit 61a8426c92ba30d403a1f072e29d713184539cc1
# Author: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
# Date:   Mon Nov 26 20:05:04 2018 +0530
# 
#     powerpc/mm/hash: Handle user access of kernel address gracefully
#     
#     In commit 2865d08dd9ea ("powerpc/mm: Move the DSISR_PROTFAULT sanity
#     check") we moved the protection fault access check before the vma
#     lookup. That means we hit that WARN_ON when user space accesses a
#     kernel address. Before that commit this was handled by find_vma() not
#     finding vma for the kernel address and considering that access as bad
#     area access.
#     
#     Avoid the confusing WARN_ON and convert that to a ratelimited printk.
#     
#     With the patch we now get:
#     
#     for load:
#       a.out[5997]: User access of kernel address (c00000000000dea0) - exploit attempt? (uid: 1000)
#       a.out[5997]: segfault (11) at c00000000000dea0 nip 1317c0798 lr 7fff80d6441c code 1 in a.out[1317c0000+10000]
#       a.out[5997]: code: 60000000 60420000 3c4c0002 38427790 4bffff20 3c4c0002 38427784 fbe1fff8
#       a.out[5997]: code: f821ffc1 7c3f0b78 60000000 e9228030 <89290000> 993f002f 60000000 383f0040
#     
#     for exec:
#       a.out[6067]: User access of kernel address (c00000000000dea0) - exploit attempt? (uid: 1000)
#       a.out[6067]: segfault (11) at c00000000000dea0 nip c00000000000dea0 lr 129d507b0 code 1
#       a.out[6067]: Bad NIP, not dumping instructions.
#     
#     Fixes: 2865d08dd9ea ("powerpc/mm: Move the DSISR_PROTFAULT sanity check")
#     Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
#     Tested-by: Breno Leitao <leitao@debian.org>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < git log --format=%s --max-count=1 61a8426c92ba30d403a1f072e29d713184539cc1
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_44x_sequoia_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  44x/sequoia_defconfig
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_44x_sequoia_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
INFO: Uncompressed kernel (size 0x4a3e90) overlaps the address of the wrapper(0x400000)
INFO: Fixing the link_address of wrapper to (0x500000)
Image Name:   Linux-4.20.0-rc2-g61a8426c92ba
Created:      Thu Dec 13 02:08:22 2018
Image Type:   PowerPC Linux Kernel Image (gzip compressed)
Data Size:    2377772 Bytes = 2322.04 KiB = 2.27 MiB
Load Address: 00500000
Entry Point:  00501540
Completed OK
# rm -rf /kisskb/build/powerpc-next_44x_sequoia_defconfig_powerpc-gcc5
# Build took: 0:00:34.071573