[YSQL][SQLsmith] Segmentation fault after infinite loop in sigusr1_handler()

[def-]

Jira Link: DB-942

Description

Found with SQLsmith, crashes in Postgres binary, code state 596eecc, Release build. There is already a bug #11366 about the signal handler, but this seems distinct. I'm guessing it runs out of stack space since sigusr1_handler keeps calling itself again:

Core was generated by `/nfusr/dev-server/dfelsing/code/yugabyte-db/build/release-clang12-linuxbrew-dyn'.
Program terminated with signal 11, Segmentation fault.
#0  0x00007fac6c5cd350 in __sigprocmask (how=2, set=0xb53c58 <UnBlockSig>, oset=0x0) at ../sysdeps/unix/sysv/linux/x86_64/sigprocmask.c:36
#1  0x000000000088d59c in sigusr1_handler (postgres_signal_arg=<optimized out>) at ../../../../../../src/postgres/src/backend/postmaster/postmaster.c:5267
#2  <signal handler called>
#3  0x00007fac6c5cd350 in __sigprocmask (how=2, set=0xb53c58 <UnBlockSig>, oset=0x0) at ../sysdeps/unix/sysv/linux/x86_64/sigprocmask.c:36
#4  0x000000000088d59c in sigusr1_handler (postgres_signal_arg=<optimized out>) at ../../../../../../src/postgres/src/backend/postmaster/postmaster.c:5267
#5  <signal handler called>
#6  0x00007fac6c5cd350 in __sigprocmask (how=2, set=0xb53c58 <UnBlockSig>, oset=0x0) at ../sysdeps/unix/sysv/linux/x86_64/sigprocmask.c:36
#7  0x000000000088d59c in sigusr1_handler (postgres_signal_arg=<optimized out>) at ../../../../../../src/postgres/src/backend/postmaster/postmaster.c:5267
[...]
#15087 0x00007fac6c5cd350 in __sigprocmask (how=2, set=0xb53c58 <UnBlockSig>, oset=0x0) at ../sysdeps/unix/sysv/linux/x86_64/sigprocmask.c:36
#15088 0x000000000088d59c in sigusr1_handler (postgres_signal_arg=<optimized out>) at ../../../../../../src/postgres/src/backend/postmaster/postmaster.c:5267
#15089 <signal handler called>
#15090 0x00007fac6c679253 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:84
#15091 0x000000000088eef9 in ServerLoop () at ../../../../../../src/postgres/src/backend/postmaster/postmaster.c:1711
#15092 0x000000000088c0b1 in PostmasterMain (argc=<optimized out>, argv=0x31406c0) at ../../../../../../src/postgres/src/backend/postmaster/postmaster.c:1417
#15093 0x00000000007ac8d3 in PostgresServerProcessMain (argc=23, argv=0x31406c0) at ../../../../../../src/postgres/src/backend/main/main.c:234
#15094 0x00000000004de432 in main ()

Core dump: core.30570.zip