From 43cefe8b1978ff920db0a30c1e201d3f166e840a Mon Sep 17 00:00:00 2001 From: Ryan Libby Date: Mon, 25 Nov 2019 07:38:27 +0000 Subject: [PATCH] sysctl sysctls: wire old buf before output with sysctl lock Several sysctl sysctls output to a user buffer while holding a non-sleepable lock that protects the sysctl topology. They need to wire the output buffer, or else they may try to sleep on a page fault. Reviewed by: cem, markj Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D22528 --- sys/kern/kern_sysctl.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c index e7f1319eaa1..dacd20724f5 100644 --- a/sys/kern/kern_sysctl.c +++ b/sys/kern/kern_sysctl.c @@ -1023,12 +1023,16 @@ sysctl_sysctl_name(SYSCTL_HANDLER_ARGS) { int *name = (int *) arg1; u_int namelen = arg2; - int error = 0; + int error; struct sysctl_oid *oid; struct sysctl_oid_list *lsp = &sysctl__children, *lsp2; struct rm_priotracker tracker; char buf[10]; + error = sysctl_wire_old_buffer(req, 0); + if (error) + return (error); + SYSCTL_RLOCK(&tracker); while (namelen) { if (!lsp) { @@ -1265,6 +1269,10 @@ sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS) struct rm_priotracker tracker; int error; + error = sysctl_wire_old_buffer(req, 0); + if (error) + return (error); + SYSCTL_RLOCK(&tracker); error = sysctl_find_oid(arg1, arg2, &oid, NULL, req); if (error) @@ -1294,6 +1302,10 @@ sysctl_sysctl_oiddescr(SYSCTL_HANDLER_ARGS) struct rm_priotracker tracker; int error; + error = sysctl_wire_old_buffer(req, 0); + if (error) + return (error); + SYSCTL_RLOCK(&tracker); error = sysctl_find_oid(arg1, arg2, &oid, NULL, req); if (error) @@ -1319,6 +1331,10 @@ sysctl_sysctl_oidlabel(SYSCTL_HANDLER_ARGS) struct rm_priotracker tracker; int error; + error = sysctl_wire_old_buffer(req, 0); + if (error) + return (error); + SYSCTL_RLOCK(&tracker); error = sysctl_find_oid(arg1, arg2, &oid, NULL, req); if (error)