# git rev-parse -q --verify 6754297c2924cd55843499bc2bb338843177931f^{commit}
6754297c2924cd55843499bc2bb338843177931f
already have revision, skipping fetch
# git checkout -q -f -B kisskb 6754297c2924cd55843499bc2bb338843177931f
# git clean -qxdf
# < git log -1
# commit 6754297c2924cd55843499bc2bb338843177931f
# Author: Daniel Axtens <dja@axtens.net>
# Date:   Mon Jun 3 16:56:57 2019 +1000
# 
#     powerpc/pseries/hvconsole: Fix stack overread via udbg
#     
#     While developing KASAN for 64-bit book3s, I hit the following stack
#     over-read.
#     
#     It occurs because the hypercall to put characters onto the terminal
#     takes 2 longs (128 bits/16 bytes) of characters at a time, and so
#     hvc_put_chars() would unconditionally copy 16 bytes from the argument
#     buffer, regardless of supplied length. However, udbg_hvc_putc() can
#     call hvc_put_chars() with a single-byte buffer, leading to the error.
#     
#       ==================================================================
#       BUG: KASAN: stack-out-of-bounds in hvc_put_chars+0xdc/0x110
#       Read of size 8 at addr c0000000023e7a90 by task swapper/0
#     
#       CPU: 0 PID: 0 Comm: swapper Not tainted 5.2.0-rc2-next-20190528-02824-g048a6ab4835b #113
#       Call Trace:
#         dump_stack+0x104/0x154 (unreliable)
#         print_address_description+0xa0/0x30c
#         __kasan_report+0x20c/0x224
#         kasan_report+0x18/0x30
#         __asan_report_load8_noabort+0x24/0x40
#         hvc_put_chars+0xdc/0x110
#         hvterm_raw_put_chars+0x9c/0x110
#         udbg_hvc_putc+0x154/0x200
#         udbg_write+0xf0/0x240
#         console_unlock+0x868/0xd30
#         register_console+0x970/0xe90
#         register_early_udbg_console+0xf8/0x114
#         setup_arch+0x108/0x790
#         start_kernel+0x104/0x784
#         start_here_common+0x1c/0x534
#     
#       Memory state around the buggy address:
#        c0000000023e7980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
#        c0000000023e7a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
#       >c0000000023e7a80: f1 f1 01 f2 f2 f2 00 00 00 00 00 00 00 00 00 00
#                                ^
#        c0000000023e7b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
#        c0000000023e7b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
#       ==================================================================
#     
#     Document that a 16-byte buffer is requred, and provide it in udbg.
#     
#     Signed-off-by: Daniel Axtens <dja@axtens.net>
#     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
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 6754297c2924cd55843499bc2bb338843177931f
# < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_powernv_defconfig_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  powernv_defconfig
# make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_powernv_defconfig_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
/kisskb/src/kernel/futex.c: In function 'do_futex':
/kisskb/src/kernel/futex.c:1658:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized]
   return oldval == cmparg;
                 ^
/kisskb/src/kernel/futex.c:1633:6: note: 'oldval' was declared here
  int oldval, ret;
      ^
WARNING: vmlinux.o(.text+0x3128): Section mismatch in reference from the variable start_here_multiplatform to the function .init.text:early_setup()
The function start_here_multiplatform() references
the function __init early_setup().
This is often because start_here_multiplatform lacks a __init 
annotation or the annotation of early_setup is wrong.

WARNING: vmlinux.o(.text+0x3164): Section mismatch in reference from the variable start_here_common to the function .init.text:start_kernel()
The function start_here_common() references
the function __init start_kernel().
This is often because start_here_common lacks a __init 
annotation or the annotation of start_kernel is wrong.

Completed OK
# rm -rf /kisskb/build/powerpc-next_powernv_defconfig_ppc64le-gcc5
# Build took: 0:01:36.356946