# 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 # 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 # Signed-off-by: Hillf Danton # Signed-off-by: David Howells # Tested-by: Sachin Sant # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux-gcc --version # < /opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux-ld --version # < git log --format=%s --max-count=1 d41a3effbb53b1bcea41e328d16a4d046a508381 # < make -s -j 10 ARCH=xtensa O=/kisskb/build/linus_xtensa-allnoconfig_xtensa CROSS_COMPILE=/opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux- allnoconfig # make -s -j 10 ARCH=xtensa O=/kisskb/build/linus_xtensa-allnoconfig_xtensa CROSS_COMPILE=/opt/cross/kisskb/br-xtensa-full-2016.08-613-ge98b4dd/bin/xtensa-linux- Completed OK # rm -rf /kisskb/build/linus_xtensa-allnoconfig_xtensa # Build took: 0:00:14.866111