btashton commented on issue #2663:
URL:
https://github.com/apache/incubator-nuttx/issues/2663#issuecomment-770651598
@xiaoxiang781216 I just noticed something similar when trying to create a
kernel thread off of a call in `sim_bringup()` (I'm add usbhost support via
libusb). I get a segfault because in `sched_dupfiles` `rtcb->group` is 0 which
means parent and child are both invalid
```c
Thread 1 "nuttx" received signal SIGSEGV, Segmentation fault.
sched_dupfiles
(tcb=0x7ffff3e295d0) at group/group_setuptaskfiles.c:103
103 if (parent[i].f_inode &&
Missing separate debuginfos, use: dnf debuginfo-install
libgcc-10.2.1-9.fc33.x86_64 libusbx-1.0.23-2.fc33.x86_64
systemd-libs-246.7-2.fc33.x86_64 zlib-1.2.11-23.fc33.x86_64
(gdb) p parent
$1 = (struct file *) 0x78
(gdb) list
98 /* Check if this file is opened by the parent. We can tell if
99 * if the file is open because it contain a reference to a
non-NULL
100 * i-node structure.
101 */
102
103 if (parent[i].f_inode &&
104 (parent[i].f_oflags & O_CLOEXEC) == 0)
105 {
106 /* Yes... duplicate it for the child */
107
(gdb) p rtcb
$2 = (struct tcb_s *) 0x7ffff3e27c90
(gdb) p rtcb->group
$3 = (struct task_group_s *) 0x0
(gdb) p rtcb*
A syntax error in expression, near `'.
(gdb) p *rtcb
$4 = {flink = 0x43f8a0 <g_idletcb>, blink = 0x7ffff7f38020 <_IO_strn_jumps>,
group = 0x0, pid = 1, start = 0x402184 <nxtask_start>, entry = {pthread =
0x408e78 <nsh_main>, main = 0x408e78 <nsh_main>}, sched_priority = 100 'd',
init_priority = 100 'd', task_state = 3 '\003', flags = 0, lockcount = 0,
errcode = 0, waitdog = {next = 0x0, func = 0x85b82ce26aee8900, lag = 0, flags =
0 '\000', arg = 9635500753727424768}, adj_stack_size = 140737285094944,
stack_alloc_ptr = 0x85b82ce26aee8900, adj_stack_ptr = 0x4412a0, waitsem =
0x0, sigprocmask = 4091706928, sigwaitmask = 32767, sigpendactionq = {head =
0x4412a0, tail = 0xffffffff}, sigpostedq = {head = 0x3, tail = 0x4441d0},
sigunbinfo = {
si_signo = 5 '\005', si_code = 23 '\027', si_errno = 232 '\350',
si_value = {sival_int = 48, sival_ptr = 0x3000000030}, si_pid = 32304,
si_status = 32767}, msgwaitq = 0x7ffff3e27d60, mhead = 0x85b82ce26aee8900, xcp
= {
sigdeliver = 0x7ffff3e27e1c, regs = {4539616, 0, 0, 0, 140737353413158,
4473296, 140737351999557, 140737351996080}}, name =
"x\030\371\367\377\177\000\000\000\000\000\000\000\000\000\000
\203\363\367\t\000\000\000\340DE\000\000\000\000"}
(gdb) p rtcb->group
$5 = (struct task_group_s *) 0x0
```
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