On Fri, Jun 30, 2023 at 1:43 AM Jiri Slaby <jirislaby@xxxxxxxxxx> wrote:
On 30. 06. 23, 10:28, Jiri Slaby wrote:
> 2348
clone3({flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, child_tid=0x7fcaa5882990, parent_tid=0x7fcaa5882990, exit_signal=0, stack=0x7fcaa5082000, stack_size=0x7ffe00, tls=0x7fcaa58826c0} => {parent_tid=[2351]}, 88) = 2351
> 2350 <... clone3 resumed> => {parent_tid=[2372]}, 88) = 2372
> 2351 <... clone3 resumed> => {parent_tid=[2354]}, 88) = 2354
> 2351 <... clone3 resumed> => {parent_tid=[2357]}, 88) = 2357
> 2354 <... clone3 resumed> => {parent_tid=[2355]}, 88) = 2355
> 2355 <... clone3 resumed> => {parent_tid=[2370]}, 88) = 2370
> 2370 mmap(NULL, 262144, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 <unfinished ...>
> 2370 <... mmap resumed>) = 0x7fca68249000
> 2372 <... clone3 resumed> => {parent_tid=[2384]}, 88) = 2384
> 2384 <... clone3 resumed> => {parent_tid=[2388]}, 88) = 2388
> 2388 <... clone3 resumed> => {parent_tid=[2392]}, 88) = 2392
> 2392 <... clone3 resumed> => {parent_tid=[2395]}, 88) = 2395
> 2395 write(2, "runtime: marked free object in s"..., 36 <unfinished
...>
I.e. IIUC, all are threads (CLONE_VM) and thread 2370 mapped ANON
0x7fca68249000 - 0x7fca6827ffff and go in thread 2395 thinks for some
reason 0x7fca6824bec8 in that region is "bad".
Thanks for the analysis Jiri.
Is it possible from these logs to identify whether 2370 finished the
mmap operation before 2395 tried to access 0x7fca6824bec8? That access
has to happen only after mmap finishes mapping the region.