mirror of
https://github.com/freebsd/freebsd-src
synced 2024-10-17 05:43:59 +00:00
An sbuf configured with SBUF_AUTOEXTEND will call malloc with M_WAITOK when a
write to the buffer causes it to overflow. We therefore can't hold the CC list rwlock over a call to sbuf_printf() for an sbuf configured with SBUF_AUTOEXTEND. Switch to a fixed length sbuf which should be of sufficient size except in the very unlikely event that the sysctl is being processed as one or more new algorithms are loaded. If that happens, we accept the race and may fail the sysctl gracefully if there is insufficient room to print the names of all the algorithms. This should address a WITNESS warning and the potential panic that would occur if the sbuf call to malloc did sleep whilst holding the CC list rwlock. Sponsored by: FreeBSD Foundation Reported by: Nick Hibma Reviewed by: bz MFC after: 3 weeks X-MFC with: r215166
This commit is contained in:
parent
b7f0fc351e
commit
a66ac850d7
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=217748
|
@ -128,20 +128,37 @@ cc_list_available(SYSCTL_HANDLER_ARGS)
|
|||
{
|
||||
struct cc_algo *algo;
|
||||
struct sbuf *s;
|
||||
int err, first;
|
||||
int err, first, nalgos;
|
||||
|
||||
err = 0;
|
||||
err = nalgos = 0;
|
||||
first = 1;
|
||||
s = sbuf_new(NULL, NULL, TCP_CA_NAME_MAX, SBUF_AUTOEXTEND);
|
||||
|
||||
CC_LIST_RLOCK();
|
||||
STAILQ_FOREACH(algo, &cc_list, entries) {
|
||||
nalgos++;
|
||||
}
|
||||
CC_LIST_RUNLOCK();
|
||||
|
||||
s = sbuf_new(NULL, NULL, nalgos * TCP_CA_NAME_MAX, SBUF_FIXEDLEN);
|
||||
|
||||
if (s == NULL)
|
||||
return (ENOMEM);
|
||||
|
||||
/*
|
||||
* It is theoretically possible for the CC list to have grown in size
|
||||
* since the call to sbuf_new() and therefore for the sbuf to be too
|
||||
* small. If this were to happen (incredibly unlikely), the sbuf will
|
||||
* reach an overflow condition, sbuf_printf() will return an error and
|
||||
* the sysctl will fail gracefully.
|
||||
*/
|
||||
CC_LIST_RLOCK();
|
||||
STAILQ_FOREACH(algo, &cc_list, entries) {
|
||||
err = sbuf_printf(s, first ? "%s" : ", %s", algo->name);
|
||||
if (err)
|
||||
if (err) {
|
||||
/* Sbuf overflow condition. */
|
||||
err = EOVERFLOW;
|
||||
break;
|
||||
}
|
||||
first = 0;
|
||||
}
|
||||
CC_LIST_RUNLOCK();
|
||||
|
|
Loading…
Reference in a new issue