sergiotarxz/nuttx
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fdcheck: fix race condition in fdcheck

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reason: ioctl will use the fl_lock file lock, causing context switching,
further leading to the failure of g_fdcheck_lock protection

Configuring NuttX and compile:
$ ./tools/configure.sh -l qemu-armv8a:nsh_smp
$ make
Running with qemu
$ qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic \
   -machine virt,virtualization=on,gic-version=3 \
   -net none -chardev stdio,id=con,mux=on -serial chardev:con \
   -mon chardev=con,mode=readline -kernel ./nuttx

Signed-off-by: hujun5 <hujun5@xiaomi.com>
This commit is contained in:
hujun5 2024-04-12 14:32:39 +08:00 committed by Alan Carvalho de Assis
parent d65f8bd4c1
commit 08e6f56176
1 changed files with 6 additions and 2 deletions
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8
libs/libc/misc/lib_fdcheck.c
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@ -102,6 +102,8 @@ int fdcheck_protect(int fd)
DEBUGASSERT(ret >= 0);
if (tag == 0)
{
uint8_t fdcheck_tag;
irqstate_t flags = spin_lock_irqsave(&g_fdcheck_lock);
if ((++g_fdcheck_tag & TAG_MASK) == 0)
{
@ -110,9 +112,11 @@ int fdcheck_protect(int fd)
g_fdcheck_tag &= TAG_MASK;
protect_fd |= g_fdcheck_tag << TAG_SHIFT;
ret = ioctl(fd, FIOC_SETTAG_FDCHECK, &g_fdcheck_tag);
DEBUGASSERT(ret == 0);
fdcheck_tag = g_fdcheck_tag;
spin_unlock_irqrestore(&g_fdcheck_lock, flags);
ret = ioctl(fd, FIOC_SETTAG_FDCHECK, &fdcheck_tag);
DEBUGASSERT(ret == 0);
}
else
{