# git rev-parse -q --verify d41a3effbb53b1bcea41e328d16a4d046a508381^{commit}
d41a3effbb53b1bcea41e328d16a4d046a508381
already have revision, skipping fetch
# git checkout -q -f -B kisskb d41a3effbb53b1bcea41e328d16a4d046a508381
# git clean -qxdf
# < git log -1
# commit d41a3effbb53b1bcea41e328d16a4d046a508381
# Author: Hillf Danton <hdanton@sina.com>
# Date:   Mon Sep 2 13:37:29 2019 +0100
# 
#     keys: Fix missing null pointer check in request_key_auth_describe()
#     
#     If a request_key authentication token key gets revoked, there's a window in
#     which request_key_auth_describe() can see it with a NULL payload - but it
#     makes no check for this and something like the following oops may occur:
#     
#             BUG: Kernel NULL pointer dereference at 0x00000038
#             Faulting instruction address: 0xc0000000004ddf30
#             Oops: Kernel access of bad area, sig: 11 [#1]
#             ...
#             NIP [...] request_key_auth_describe+0x90/0xd0
#             LR [...] request_key_auth_describe+0x54/0xd0
#             Call Trace:
#             [...] request_key_auth_describe+0x54/0xd0 (unreliable)
#             [...] proc_keys_show+0x308/0x4c0
#             [...] seq_read+0x3d0/0x540
#             [...] proc_reg_read+0x90/0x110
#             [...] __vfs_read+0x3c/0x70
#             [...] vfs_read+0xb4/0x1b0
#             [...] ksys_read+0x7c/0x130
#             [...] system_call+0x5c/0x70
#     
#     Fix this by checking for a NULL pointer when describing such a key.
#     
#     Also make the read routine check for a NULL pointer to be on the safe side.
#     
#     [DH: Modified to not take already-held rcu lock and modified to also check
#      in the read routine]
#     
#     Fixes: 04c567d9313e ("[PATCH] Keys: Fix race between two instantiators of a key")
#     Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
#     Signed-off-by: Hillf Danton <hdanton@sina.com>
#     Signed-off-by: David Howells <dhowells@redhat.com>
#     Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-ld --version
# < git log --format=%s --max-count=1 d41a3effbb53b1bcea41e328d16a4d046a508381
# < make -s -j 10 ARCH=parisc O=/kisskb/build/linus_a500_defconfig_parisc64 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-  a500_defconfig
# make -s -j 10 ARCH=parisc O=/kisskb/build/linus_a500_defconfig_parisc64 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa64-linux/bin/hppa64-linux-  
In file included from /kisskb/src/arch/parisc/include/asm/atomic.h:10,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/arch/parisc/include/asm/bitops.h:13,
                 from /kisskb/src/include/linux/bitops.h:19,
                 from /kisskb/src/include/linux/kernel.h:12,
                 from /kisskb/src/include/linux/list.h:9,
                 from /kisskb/src/include/linux/preempt.h:11,
                 from /kisskb/src/include/linux/spinlock.h:51,
                 from /kisskb/src/include/linux/seqlock.h:36,
                 from /kisskb/src/include/linux/time.h:6,
                 from /kisskb/src/fs/nfs/read.c:11:
/kisskb/src/fs/nfs/read.c: In function 'nfs_read_completion':
/kisskb/src/arch/parisc/include/asm/cmpxchg.h:48:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
  ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/fs/nfs/read.c:196:5: note: in expansion of macro 'xchg'
     xchg(&nfs_req_openctx(req)->error, error);
     ^~~~
/kisskb/src/fs/nfs/read.c: In function 'nfs_readpage':
/kisskb/src/arch/parisc/include/asm/cmpxchg.h:48:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
  ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/fs/nfs/read.c:352:2: note: in expansion of macro 'xchg'
  xchg(&ctx->error, 0);
  ^~~~
In file included from /kisskb/src/arch/parisc/include/asm/atomic.h:10,
                 from /kisskb/src/include/linux/atomic.h:7,
                 from /kisskb/src/arch/parisc/include/asm/bitops.h:13,
                 from /kisskb/src/include/linux/bitops.h:19,
                 from /kisskb/src/include/linux/kernel.h:12,
                 from /kisskb/src/include/linux/list.h:9,
                 from /kisskb/src/include/linux/module.h:9,
                 from /kisskb/src/drivers/scsi/scsi_debug.c:18:
/kisskb/src/drivers/scsi/scsi_debug.c: In function 'resp_start_stop':
/kisskb/src/arch/parisc/include/asm/cmpxchg.h:48:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
/kisskb/src/arch/parisc/include/asm/atomic.h:78:30: note: in expansion of macro 'xchg'
 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
                              ^~~~
/kisskb/src/drivers/scsi/scsi_debug.c:1618:2: note: in expansion of macro 'atomic_xchg'
  atomic_xchg(&devip->stopped, stop);
  ^~~~~~~~~~~
Completed OK
# rm -rf /kisskb/build/linus_a500_defconfig_parisc64
# Build took: 0:01:31.575595