# git rev-parse -q --verify fa520c47eaa15b9baa8ad66ac18da4a31679693b^{commit}
fa520c47eaa15b9baa8ad66ac18da4a31679693b
already have revision, skipping fetch
# git checkout -q -f -B kisskb fa520c47eaa15b9baa8ad66ac18da4a31679693b
# git clean -qxdf
# < git log -1
# commit fa520c47eaa15b9baa8ad66ac18da4a31679693b
# Author: Eric Sandeen <sandeen@redhat.com>
# Date:   Wed Oct 17 15:23:59 2018 +0100
# 
#     fscache: Fix out of bound read in long cookie keys
#     
#     fscache_set_key() can incur an out-of-bounds read, reported by KASAN:
#     
#      BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x5b3/0x680 [fscache]
#      Read of size 4 at addr ffff88084ff056d4 by task mount.nfs/32615
#     
#     and also reported by syzbot at https://lkml.org/lkml/2018/7/8/236
#     
#       BUG: KASAN: slab-out-of-bounds in fscache_set_key fs/fscache/cookie.c:120 [inline]
#       BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x7a9/0x880 fs/fscache/cookie.c:171
#       Read of size 4 at addr ffff8801d3cc8bb4 by task syz-executor907/4466
#     
#     This happens for any index_key_len which is not divisible by 4 and is
#     larger than the size of the inline key, because the code allocates exactly
#     index_key_len for the key buffer, but the hashing loop is stepping through
#     it 4 bytes (u32) at a time in the buf[] array.
#     
#     Fix this by calculating how many u32 buffers we'll need by using
#     DIV_ROUND_UP, and then using kcalloc() to allocate a precleared allocation
#     buffer to hold the index_key, then using that same count as the hashing
#     index limit.
#     
#     Fixes: ec0328e46d6e ("fscache: Maintain a catalogue of allocated cookies")
#     Reported-by: syzbot+a95b989b2dde8e806af8@syzkaller.appspotmail.com
#     Signed-off-by: Eric Sandeen <sandeen@redhat.com>
#     Cc: stable <stable@vger.kernel.org>
#     Signed-off-by: David Howells <dhowells@redhat.com>
#     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux-gcc --version
# < git log --format=%s --max-count=1 fa520c47eaa15b9baa8ad66ac18da4a31679693b
# < make -s -j 80 ARCH=arm64 O=/kisskb/build/linus_arm64-allmodconfig_arm64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  allmodconfig
# make -s -j 80 ARCH=arm64 O=/kisskb/build/linus_arm64-allmodconfig_arm64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  
/kisskb/src/scripts/unifdef.c: In function 'Mpass':
/kisskb/src/scripts/unifdef.c:453:28: warning: 'strncpy' output truncated before terminating nul copying 4 bytes from a string of the same length [-Wstringop-truncation]
 static void Mpass (void) { strncpy(keyword, "if  ", 4); Pelif(); }
                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /kisskb/src/arch/arm64/include/asm/processor.h:41,
                 from /kisskb/src/include/linux/rcupdate.h:43,
                 from /kisskb/src/include/linux/rculist.h:11,
                 from /kisskb/src/include/linux/pid.h:5,
                 from /kisskb/src/include/linux/sched.h:14,
                 from /kisskb/src/kernel/debug/kdb/kdb_support.c:15:
In function 'strncpy',
    inlined from 'kallsyms_symbol_next' at /kisskb/src/kernel/debug/kdb/kdb_support.c:239:4:
/kisskb/src/include/linux/string.h:246:9: warning: '__builtin_strncpy' specified bound depends on the length of the source argument [-Wstringop-overflow=]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/kernel/debug/kdb/kdb_support.c: In function 'kallsyms_symbol_next':
/kisskb/src/include/linux/string.h:267:10: note: length computed here
   return __builtin_strlen(p);
          ^~~~~~~~~~~~~~~~~~~
/kisskb/src/lib/ubsan.c:432:1: warning: ignoring attribute 'noreturn' in declaration of a built-in function '__ubsan_handle_builtin_unreachable' because it conflicts with attribute 'const' [-Wattributes]
 {
 ^
<built-in>: note: previous declaration here
In file included from /kisskb/src/arch/arm64/include/asm/processor.h:41,
                 from /kisskb/src/include/linux/rcupdate.h:43,
                 from /kisskb/src/include/linux/rculist.h:11,
                 from /kisskb/src/include/linux/pid.h:5,
                 from /kisskb/src/include/linux/sched.h:14,
                 from /kisskb/src/arch/arm64/include/asm/compat.h:25,
                 from /kisskb/src/arch/arm64/include/asm/stat.h:24,
                 from /kisskb/src/include/linux/stat.h:6,
                 from /kisskb/src/include/linux/module.h:10,
                 from /kisskb/src/lib/test_hexdump.c:8:
In function 'strncpy',
    inlined from 'test_hexdump_prepare_test.isra.0' at /kisskb/src/lib/test_hexdump.c:102:3:
/kisskb/src/include/linux/string.h:246:9: warning: '__builtin_strncpy' specified bound depends on the length of the source argument [-Wstringop-overflow=]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/lib/test_hexdump.c: In function 'test_hexdump_prepare_test.isra.0':
/kisskb/src/include/linux/string.h:267:10: note: length computed here
   return __builtin_strlen(p);
          ^~~~~~~~~~~~~~~~~~~
/kisskb/src/drivers/isdn/hardware/eicon/message.c: In function 'sig_ind':
/kisskb/src/drivers/isdn/hardware/eicon/message.c:5985:1: warning: the frame size of 2096 bytes is larger than 2048 bytes [-Wframe-larger-than=]
 }
 ^
Completed OK
# rm -rf /kisskb/build/linus_arm64-allmodconfig_arm64-gcc8
# Build took: 0:19:11.876643