Mirrors/criu
1
0
Fork 0
mirror of https://github.com/checkpoint-restore/criu.git synced 2026-07-18 00:58:31 +00:00
Code Issues Projects Releases Wiki Activity

zdtm: unregister rseq before zeroing the rseq area

Browse source 
Starting with Linux 7.1, the kernel enforces strict read-only field
protection for the rseq V2 ABI. Userspace is no longer allowed to
modify kernel-managed fields (cpu_id_start, cpu_id, node_id, mm_cid)
while rseq is registered. Violations are detected on the next context
switch and the offending process is killed with SIGSEGV.

The rseq01 test was zeroing the entire glibc-registered rseq area
with memset() before calling test_init(), which internally calls
fork(). This corrupted the read-only fields while the glibc rseq
registration was still active, causing the kernel to send SIGSEGV
during the fork.

Fix this by calling unregister_old_rseq() before the memset in both
main() and thread_routine(), so the kernel is no longer monitoring
those fields when they are zeroed. The subsequent register_thread()
call re-registers rseq with the clean area.

Link: 7f00232152

Assisted-by: Claude Code (https://claude.ai/code):claude-opus-4-6
Signed-off-by: Adrian Reber <areber@redhat.com>
This commit is contained in:
Adrian Reber 2026-05-19 17:11:35 +00:00 • committed by Andrei Vagin
parent 3db4b0922b
commit da5b7bf829
1 changed files with 2 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

2
test/zdtm/transition/rseq01.c
View file

@ -252,6 +252,7 @@ void *thread_routine(void *args)
int cpu;
rseq_ptr = rseq_area();
unregister_old_rseq();
memset((void *)rseq_ptr, 0, rseq_reg_size());
register_thread();
task_waiter_complete(&waiter, 1);
@ -277,6 +278,7 @@ int main(int argc, char *argv[])
pthread_t thread;
rseq_ptr = rseq_area();
unregister_old_rseq();
memset((void *)rseq_ptr, 0, rseq_reg_size());
test_init(argc, argv);