diff options
Diffstat (limited to 'results/classifier/deepseek-2/output/other/1813398')
| -rw-r--r-- | results/classifier/deepseek-2/output/other/1813398 | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/results/classifier/deepseek-2/output/other/1813398 b/results/classifier/deepseek-2/output/other/1813398 new file mode 100644 index 000000000..8398fedcc --- /dev/null +++ b/results/classifier/deepseek-2/output/other/1813398 @@ -0,0 +1,42 @@ + +qemu user calls malloc after fork in multi-threaded process + +qemu user may hang in malloc on a musl based system because +it calls malloc after fork (in a pthread_atfork handler) +in the child process. + +this is undefined behaviour since the parent process is +multi-threaded and only as-safe functions may be called +in the child then. (if malloc/free is called concurrently +with fork the malloc state will be corrupted in the child, +it works on glibc because glibc takes the malloc locks +before the fork syscall, but that breaks the as-safety of +fork and thus non-conforming to posix) + +discussed at +https://www.openwall.com/lists/musl/2019/01/26/1 + +the bug is hard to reproduce (requires the call_rcu thread +to call free concurrently with do_fork in the main thread), +this one is observed with qemu-arm 3.1.0 running on x86_64 +executing an arm busybox sh: + +(gdb) bt +#0 malloc (n=<optimized out>, n@entry=9) at src/malloc/malloc.c:306 +#1 0x0000000060184ad3 in g_malloc (n_bytes=n_bytes@entry=9) at gmem.c:99 +#2 0x000000006018bcab in g_strdup (str=<optimized out>, str@entry=0x60200abf "call_rcu") at gstrfuncs.c:363 +#3 0x000000006016e31d in qemu_thread_create (thread=thread@entry=0x7ffe367d1870, name=name@entry=0x60200abf "call_rcu", + start_routine=start_routine@entry=0x60174c00 <call_rcu_thread>, arg=arg@entry=0x0, mode=mode@entry=1) + at /home/pmos/build/src/qemu-3.1.0/util/qemu-thread-posix.c:526 +#4 0x0000000060174b99 in rcu_init_complete () at /home/pmos/build/src/qemu-3.1.0/util/rcu.c:327 +#5 0x00000000601c4fac in __fork_handler (who=1) at src/thread/pthread_atfork.c:26 +#6 0x00000000601be8db in fork () at src/process/fork.c:33 +#7 0x000000006009d191 in do_fork (env=0x627aaed0, flags=flags@entry=17, newsp=newsp@entry=0, parent_tidptr=parent_tidptr@entry=0, + newtls=newtls@entry=0, child_tidptr=child_tidptr@entry=0) at /home/pmos/build/src/qemu-3.1.0/linux-user/syscall.c:5528 +#8 0x00000000600af894 in do_syscall1 (cpu_env=cpu_env@entry=0x627aaed0, num=num@entry=2, arg1=arg1@entry=0, arg2=arg2@entry=-8700192, + arg3=<optimized out>, arg4=8, arg5=1015744, arg6=-74144, arg7=0, arg8=0) at /home/pmos/build/src/qemu-3.1.0/linux-user/syscall.c:7042 +#9 0x00000000600a835c in do_syscall (cpu_env=cpu_env@entry=0x627aaed0, num=2, arg1=0, arg2=-8700192, arg3=<optimized out>, + arg4=<optimized out>, arg5=1015744, arg6=-74144, arg7=0, arg8=0) at /home/pmos/build/src/qemu-3.1.0/linux-user/syscall.c:11533 +#10 0x00000000600c265f in cpu_loop (env=env@entry=0x627aaed0) at /home/pmos/build/src/qemu-3.1.0/linux-user/arm/cpu_loop.c:360 +#11 0x00000000600417a2 in main (argc=<optimized out>, argv=0x7ffe367d57b8, envp=<optimized out>) + at /home/pmos/build/src/qemu-3.1.0/linux-user/main.c:819 \ No newline at end of file |