Date: Thu, 23 Oct 2008 12:00:08 GMT From: Mateusz Guzik <mjguzik@gmail.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/128304: vn_pollrecord() derefs NULL if v_addpollinfo() fails Message-ID: <200810231200.m9NC08jB052021@freefall.freebsd.org>
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The following reply was made to PR kern/128304; it has been noted by GNATS. From: Mateusz Guzik <mjguzik@gmail.com> To: bug-followup@freebsd.org Cc: Subject: Re: kern/128304: vn_pollrecord() derefs NULL if v_addpollinfo() fails Date: Thu, 23 Oct 2008 13:57:43 +0200 Hi. failure of uma_zalloc() would cause null pointer dereference in v_addpollinfo() anyway (due to mtx_init() call). From commit message for rev 1.142 of sys/vm/uma_core.c: Remove uma_zalloc_arg() hack, which coerced M_WAITOK to M_NOWAIT when allocations were made using improper flags in interrupt context. Replace with a simple WITNESS warning call. This restores the invariant that M_WAITOK allocations will always succeed or die horribly trying, which is relied on by many UMA consumers. So it's ok to rely on M_WAITOK (which v_addpollinfo() does) and additional null check in vfs_kqfilter() can be removed as being meaningles. Thanks, -- Mateusz Guzik
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