Date: Sat, 08 Nov 2025 12:26:54 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 290893] netlink: genl_register_family function does not release the lock if the family name is already in use Message-ID: <bug-290893-227@https.bugs.freebsd.org/bugzilla/>
index | next in thread | raw e-mail
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=290893 Bug ID: 290893 Summary: netlink: genl_register_family function does not release the lock if the family name is already in use Product: Base System Version: 15.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: bruno.silvestre@gmail.com The function genl_register_family() returns an error if the name of the family is already in use, but does not release the lock. The next call to genl_register_family() will block indefinitely. A side comment, why does the function panic if the maximum number of families are already registered? It could just return an error. --- netlink_generic.old.c 2025-11-08 08:55:46.012479000 -0300 +++ netlink_generic.c 2025-11-08 09:00:00.541146000 -0300 @@ -366,8 +366,10 @@ GENL_LOCK(); for (u_int i = 0; i < MAX_FAMILIES; i++) if (families[i].family_name != NULL && - strcmp(families[i].family_name, family_name) == 0) + strcmp(families[i].family_name, family_name) == 0) { + GENL_UNLOCK(); return (0); + } /* Microoptimization: index 0 is reserved for the control family. */ gf = NULL; @@ -376,6 +378,10 @@ gf = &families[i]; break; } + + // + //XXX: Why kernel panic? It could return 0 as register group below. + // KASSERT(gf, ("%s: maximum of %u generic netlink families allocated", __func__, MAX_FAMILIES)); //---------------------------------------------------------------------------- To test the bug, just creates a module that register a family. You load and unload it 3 times: 1st ok, 2nd error, 3rd deadlock. #include <sys/param.h> #include <sys/module.h> #include <sys/kernel.h> #include <sys/systm.h> #include <sys/malloc.h> #include <netlink/netlink.h> #include <netlink/netlink_ctl.h> #include <netlink/netlink_generic.h> static int genltest_modevent(module_t mod __unused, int event, void *arg __unused) { int error = 0; switch (event) { case MOD_LOAD: uprintf("Generic netlink load\n"); uint16_t id = genl_register_family("genltest", 0, 2, 0); uprintf("Register: %d\n", id); break; case MOD_UNLOAD: uprintf("Generic netlink unload\n"); break; default: error = EOPNOTSUPP; break; } return (error); } static moduledata_t genltest_mod = { "genltest", genltest_modevent, NULL }; DECLARE_MODULE(genltest, genltest_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE); -- You are receiving this mail because: You are the assignee for the bug.home | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?bug-290893-227>