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https://github.com/apache/nuttx.git
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dongjiuzhu1
50c78843b4
When a child process inherits file descriptors from its parent via fdlist_copy(), the fd tags (fd_tag_fdsan and fd_tag_fdcheck) were not being copied. This caused assertion failures when the child process closed inherited file descriptors, because the fdcheck/fdsan subsystems expected the tags to match. Root Cause: ---------- The fdlist_install() function was not preserving the fd tags during fd duplication. When copying fds from parent to child in fdlist_copy(), the tags were lost, resulting in: - fd_tag_fdsan: Used for file descriptor ownership tracking (FDSAN) - fd_tag_fdcheck: Used for fd validity checking (FDCHECK) Both tags being reset to 0/NULL instead of copied from parent. Symptom: -------- Child processes would crash with assertion failure in fdcheck_restore() when closing inherited file descriptors: fdcheck_restore+0x69/0xa0 fdlist_get2+0x11/0x48 fdlist_close+0xd/0x94 close+0x15/0x30 This occurred because fdcheck_restore() validates that the fd_tag_fdcheck matches the expected value, and the mismatch triggered an assertion. Solution: --------- 1. Add a 'copy' parameter to fdlist_install() to distinguish between: - New fd allocation (copy=false): Initialize fresh tags - Fd duplication (copy=true): Preserve tags from source fd 2. Add fdp parameter to fdlist_install() to access source fd tags 3. In fdlist_copy(), pass copy=true to preserve parent's fd tags 4. In fdlist_dup3(), pass copy=false since dup operations should create independent fd tracking (not copy parent tags) Changes: -------- - fdlist_install(): Added 'fdp' and 'copy' parameters - When copy=true, preserve fd_tag_fdsan and fd_tag_fdcheck from source - fdlist_copy(): Pass copy=true to preserve parent tags - fdlist_dup3(): Pass copy=false for normal dup behavior Impact: ------- This fix ensures that file descriptor ownership tracking and validity checking work correctly across fork/clone operations, preventing crashes when child processes close inherited file descriptors. Without this fix, any program using fork() with inherited fds would crash if CONFIG_FDSAN or CONFIG_FDCHECK were enabled. Issue backtrace: backtrace_unwind+0x105/0x108 sched_backtrace+0x6f/0x80 sched_dumpstack+0x33/0x80 _assert+0x229/0x510 arm_syscall+0x81/0x98 up_assert+0xd/0x18 __assert+0x1d/0x24 fdcheck_restore+0x69/0xa0 fdlist_get2+0x11/0x48 fdlist_close+0xd/0x94 close+0x15/0x30 closefd+0x5/0x30 notify_parent_process+0x2b/0x40 run_helper_tcp4_echo_server+0x75/0x114 run_test_part+0x5f/0x68 uv_run_tests_main+0x35/0x60 run_test_part+0x5f/0x68 uv_run_tests_main+0x35/0x60 nxtask_startup+0x13/0x2c nxtask_start+0x4d/0x64 Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>