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[24.9.77.57]) by smtp.googlemail.com with ESMTPSA id t10sm405096ils.36.2021.05.11.11.51.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 May 2021 11:51:54 -0700 (PDT) From: Jim Cromie To: Jason Baron , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Jim Cromie Subject: [RFC PATCH v5 26/28] dyndbg: fixup protect header when deleting site Date: Tue, 11 May 2021 12:50:55 -0600 Message-Id: <20210511185057.3815777-27-jim.cromie@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210511185057.3815777-1-jim.cromie@gmail.com> References: <20210511185057.3815777-1-jim.cromie@gmail.com> MIME-Version: 1.0 Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=LEtG3ihO; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf28.hostedemail.com: domain of jimcromie@gmail.com designates 209.85.166.171 as permitted sender) smtp.mailfrom=jimcromie@gmail.com X-Stat-Signature: co6sosjopknz3j86u39sicireujgjqhy X-Rspamd-Queue-Id: E4B922000262 X-Rspamd-Server: rspam02 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf28; identity=mailfrom; envelope-from=""; helo=mail-il1-f171.google.com; client-ip=209.85.166.171 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620759113-159016 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: fix a null-ptr-deref when .site info is deleted. #> echo +D > /proc/dynamic_debug/control This protects the header.site pointer from zeroing; we need it for all the SITE_CHK sanity checking. Probably should protect against toggling the static_key too (in the same function), but this smaller change fixes the crash. Signed-off-by: Jim Cromie --- lib/dynamic_debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index b61e4a211819..aa4a476d70ad 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -247,7 +247,7 @@ static void ddebug_alter_site(struct _ddebug *dp, #ifdef SITE_CHK /* delete site info for this callsite */ if (modifiers->flags & _DPRINTK_FLAGS_DELETE_SITE) { - if (dp->site) { + if (dp->site && !is_dyndbg_header_pair(dp, dp->site)) { vpr_info("dropping site info %s.%s.%d\n", dp->site->filename, dp->site->function, dp->lineno); dp->site =3D NULL; --=20 2.31.1