From 3f2a5459fb00c2f529d68a4a0fd7f367a77fa65a Mon Sep 17 00:00:00 2001 From: Attila Kovacs Date: Tue, 26 Jul 2022 15:24:01 -0400 Subject: [PATCH] thread safe clnt destruction. If clnt_dg_destroy() or clnt_vc_destroy() is awoken with other blocked operations pending (such as clnt_*_call(), clnt_*_control(), or clnt_*_freeres()) but no active operation currently being executed, then the client gets destroyed. Then, as the other blocked operations get subsequently awoken, they will try operate on an invalid client handle, potentially causing unpredictable behavior and stack corruption. Signed-off-by: Attila Kovacs Signed-off-by: Steve Dickson --- src/clnt_dg.c | 13 ++++++++++++- src/clnt_fd_locks.h | 2 ++ src/clnt_vc.c | 13 ++++++++++++- 3 files changed, 26 insertions(+), 2 deletions(-) diff --git a/src/clnt_dg.c b/src/clnt_dg.c index b2043ac..166af63 100644 --- a/src/clnt_dg.c +++ b/src/clnt_dg.c @@ -101,6 +101,7 @@ extern mutex_t clnt_fd_lock; #define release_fd_lock(fd_lock, mask) { \ mutex_lock(&clnt_fd_lock); \ fd_lock->active = FALSE; \ + fd_lock->pending--; \ thr_sigsetmask(SIG_SETMASK, &(mask), NULL); \ cond_signal(&fd_lock->cv); \ mutex_unlock(&clnt_fd_lock); \ @@ -311,6 +312,7 @@ clnt_dg_call(cl, proc, xargs, argsp, xresults, resultsp, utimeout) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); + cu->cu_fd_lock->pending++; while (cu->cu_fd_lock->active) cond_wait(&cu->cu_fd_lock->cv, &clnt_fd_lock); cu->cu_fd_lock->active = TRUE; @@ -571,10 +573,12 @@ clnt_dg_freeres(cl, xdr_res, res_ptr) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); + cu->cu_fd_lock->pending++; while (cu->cu_fd_lock->active) cond_wait(&cu->cu_fd_lock->cv, &clnt_fd_lock); xdrs->x_op = XDR_FREE; dummy = (*xdr_res)(xdrs, res_ptr); + cu->cu_fd_lock->pending--; thr_sigsetmask(SIG_SETMASK, &mask, NULL); cond_signal(&cu->cu_fd_lock->cv); mutex_unlock(&clnt_fd_lock); @@ -602,6 +606,7 @@ clnt_dg_control(cl, request, info) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); + cu->cu_fd_lock->pending++; while (cu->cu_fd_lock->active) cond_wait(&cu->cu_fd_lock->cv, &clnt_fd_lock); cu->cu_fd_lock->active = TRUE; @@ -742,8 +747,14 @@ clnt_dg_destroy(cl) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); - while (cu_fd_lock->active) + /* wait until all pending operations on client are completed. */ + while (cu_fd_lock->pending > 0) { + /* If a blocked operation can be awakened, then do it. */ + if (cu_fd_lock->active == FALSE) + cond_signal(&cu_fd_lock->cv); + /* keep waiting... */ cond_wait(&cu_fd_lock->cv, &clnt_fd_lock); + } if (cu->cu_closeit) (void)close(cu_fd); XDR_DESTROY(&(cu->cu_outxdrs)); diff --git a/src/clnt_fd_locks.h b/src/clnt_fd_locks.h index 359f995..6ba62cb 100644 --- a/src/clnt_fd_locks.h +++ b/src/clnt_fd_locks.h @@ -50,6 +50,7 @@ static unsigned int fd_locks_prealloc = 0; /* per-fd lock */ struct fd_lock_t { bool_t active; + int pending; /* Number of pending operations on fd */ cond_t cv; }; typedef struct fd_lock_t fd_lock_t; @@ -180,6 +181,7 @@ fd_lock_t* fd_lock_create(int fd, fd_locks_t *fd_locks) { item->fd = fd; item->refs = 1; item->fd_lock.active = FALSE; + item->fd_lock.pending = 0; cond_init(&item->fd_lock.cv, 0, (void *) 0); TAILQ_INSERT_HEAD(list, item, link); } else { diff --git a/src/clnt_vc.c b/src/clnt_vc.c index 3c73e65..5bbc78b 100644 --- a/src/clnt_vc.c +++ b/src/clnt_vc.c @@ -153,6 +153,7 @@ extern mutex_t clnt_fd_lock; #define release_fd_lock(fd_lock, mask) { \ mutex_lock(&clnt_fd_lock); \ fd_lock->active = FALSE; \ + fd_lock->pending--; \ thr_sigsetmask(SIG_SETMASK, &(mask), (sigset_t *) NULL); \ cond_signal(&fd_lock->cv); \ mutex_unlock(&clnt_fd_lock); \ @@ -357,6 +358,7 @@ clnt_vc_call(cl, proc, xdr_args, args_ptr, xdr_results, results_ptr, timeout) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); + ct->ct_fd_lock->pending++; while (ct->ct_fd_lock->active) cond_wait(&ct->ct_fd_lock->cv, &clnt_fd_lock); ct->ct_fd_lock->active = TRUE; @@ -495,10 +497,12 @@ clnt_vc_freeres(cl, xdr_res, res_ptr) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); + ct->ct_fd_lock->pending++; while (ct->ct_fd_lock->active) cond_wait(&ct->ct_fd_lock->cv, &clnt_fd_lock); xdrs->x_op = XDR_FREE; dummy = (*xdr_res)(xdrs, res_ptr); + ct->ct_fd_lock->pending--; thr_sigsetmask(SIG_SETMASK, &(mask), NULL); cond_signal(&ct->ct_fd_lock->cv); mutex_unlock(&clnt_fd_lock); @@ -533,6 +537,7 @@ clnt_vc_control(cl, request, info) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); + ct->ct_fd_lock->pending++; while (ct->ct_fd_lock->active) cond_wait(&ct->ct_fd_lock->cv, &clnt_fd_lock); ct->ct_fd_lock->active = TRUE; @@ -655,8 +660,14 @@ clnt_vc_destroy(cl) sigfillset(&newmask); thr_sigsetmask(SIG_SETMASK, &newmask, &mask); mutex_lock(&clnt_fd_lock); - while (ct_fd_lock->active) + /* wait until all pending operations on client are completed. */ + while (ct_fd_lock->pending > 0) { + /* If a blocked operation can be awakened, then do it. */ + if (ct_fd_lock->active == FALSE) + cond_signal(&ct_fd_lock->cv); + /* keep waiting... */ cond_wait(&ct_fd_lock->cv, &clnt_fd_lock); + } if (ct->ct_closeit && ct->ct_fd != -1) { (void)close(ct->ct_fd); } -- 1.8.3.1