The branch stable/13 has been updated by dchagin: URL: https://cgit.FreeBSD.org/src/commit/?id=b1d0fe755bb11be36d97885dbab0ac66aabb5877
commit b1d0fe755bb11be36d97885dbab0ac66aabb5877 Author: Dmitry Chagin <[email protected]> AuthorDate: 2022-06-22 11:49:40 +0000 Commit: Dmitry Chagin <[email protected]> CommitDate: 2022-07-06 11:02:15 +0000 linprocfs: Skip printing of the guard page in the /proc/self/maps To calculate the base (lowest addressable) address of the stack of the initial thread glibc parses /proc/self/maps. In fact, the base address is calculated as 'to' value of stack entry of the /proc/self/maps - stack size limit (if the stack grows down). The base address should fit in between preceding entry and stack entry of the /proc/self/maps. In FreeBSD, since 19bd0d9 (Implement address space guards), we actually have two mappings for the stack region. The first one is the no-access mapping for the region the stack can grow into (guard page), and the second - initial stack region with size sgrowsiz. The first mapping confuses Glibc, in the end which is improperly calculate stack size and the base address. PR: 253337 Reviewed by: kib Differential revision: https://reviews.freebsd.org/D35537 MFC after: 2 week (cherry picked from commit ef1976ccf5420d0912afcb49733c7a88643069da) --- sys/compat/linprocfs/linprocfs.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c index 6cf25350d9e8..714c4ee4a84c 100644 --- a/sys/compat/linprocfs/linprocfs.c +++ b/sys/compat/linprocfs/linprocfs.c @@ -1307,7 +1307,13 @@ linprocfs_doprocmaps(PFS_FILL_ARGS) VM_MAP_ENTRY_FOREACH(entry, map) { name = ""; freename = NULL; - if (entry->eflags & MAP_ENTRY_IS_SUB_MAP) + /* + * Skip printing of the guard page of the stack region, as + * it confuses glibc pthread_getattr_np() method, where both + * the base address and size of the stack of the initial thread + * are calculated. + */ + if ((entry->eflags & (MAP_ENTRY_IS_SUB_MAP | MAP_ENTRY_GUARD)) != 0) continue; e_prot = entry->protection; e_start = entry->start;
