Re: KMSAN: uninit-value in af_alg_free_areq_sgls

[syzbot]

Hello,

syzbot tried to test the proposed patch but build/boot failed:

lost connection to test machine



[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok  
8[?25h[?0c.
[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok  
8[?25h[?0c.
[....] Starting OpenBSD Secure Shell server: sshd[   21.709280] random:  
sshd: uninitialized urandom read (32 bytes read)
[?25l[?1c7[ ok 8[?25h[?0c.

Debian GNU/Linux 7 syzkaller ttyS0

syzkaller login: [   26.229113] random: sshd: uninitialized urandom read  
(32 bytes read)
[   26.532843] random: sshd: uninitialized urandom read (32 bytes read)
[   27.787277] random: sshd: uninitialized urandom read (32 bytes read)
Warning: Permanently added '10.128.0.2' (ECDSA) to the list of known hosts.
[   33.299368] random: sshd: uninitialized urandom read (32 bytes read)
flag provided but not defined: -os
Usage of ./syz-fuzzer:
  -abort_signal int
    	initial signal to send to executor in error conditions; upgrades to  
SIGKILL if executor does not exit
  -arch string
    	target arch (default "amd64")
  -buffer_size uint
    	internal buffer size (in bytes) for executor output
  -collide
    	collide syscalls to provoke data races (default true)
  -cover
    	collect feedback signals (coverage)
  -debug
    	debug output from executor
  -executor string
    	path to executor binary (default "./syz-executor")
  -ipc string
    	ipc scheme (pipe/shmem)
  -leak
    	detect memory leaks
  -manager string
    	manager rpc address
  -name string
    	unique name for manager (default "test")
  -output string
    	write programs to none/stdout/dmesg/file (default "stdout")
  -pprof string
    	address to serve pprof profiles
  -procs int
    	number of parallel test processes (default 1)
  -sandbox string
    	sandbox for fuzzing (none/setuid/namespace) (default "none")
  -test
    	enable image testing mode
  -threaded
    	use threaded mode in executor (default true)
  -timeout duration
    	execution timeout
  -v int
    	verbosity



Tested on:

commit:         9c9df9f275f0 kmsan: remove kmsan_threads_ready
git tree:       https://github.com/google/kmsan.git/master
kernel config:  https://syzkaller.appspot.com/x/.config?x=b11f4cfb262ee607
compiler:       clang version 7.0.0 (trunk 334104)
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16a5af84400000