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bh=DdY3ERWTiaZOd3Bn0BxtqRsKwTUqDQ8SFHOZ6ljXqek=; b=KghfFvdOfa7FxJejRrVbm/gfSqy8g9eytkOgQDw/IIib2xzCko+0m8g9dTh2sNjQPxJWkm Rb+XQRU6oQmJr0JSF1lo0e/+3ObiZIMzh429Z5G2XpCw9HF/P7Y2hK8CWs6mdhwzr0AgVy Ii7WMY5u0i+g6QdE5c0P2l2fYFJzzb4= X-MC-Unique: q4dJ48Q4NRykTeqRCBR8Rw-1 From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 080/115] exec: set map length to zero when returning NULL Date: Thu, 11 Jun 2020 15:44:14 -0400 Message-Id: <20200611194449.31468-81-pbonzini@redhat.com> In-Reply-To: <20200611194449.31468-1-pbonzini@redhat.com> References: <20200611194449.31468-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=205.139.110.120; envelope-from=pbonzini@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/11 14:52:10 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexander Bulekov , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Prasad J Pandit , Peter Maydell Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) From: Prasad J Pandit When mapping physical memory into host's virtual address space, 'address_space_map' may return NULL if BounceBuffer is in_use. Set and return '*plen =3D 0' to avoid later NULL pointer dereference. Reported-by: Alexander Bulekov Fixes: https://bugs.launchpad.net/qemu/+bug/1878259 Suggested-by: Paolo Bonzini Suggested-by: Peter Maydell Signed-off-by: Prasad J Pandit Message-Id: <20200526111743.428367-1-ppandit@redhat.com> Reviewed-by: Philippe Mathieu-Daud=C3=A9 Signed-off-by: Paolo Bonzini --- exec.c | 1 + include/exec/memory.h | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/exec.c b/exec.c index 9cbde85d8c..778263f1c6 100644 --- a/exec.c +++ b/exec.c @@ -3540,6 +3540,7 @@ void *address_space_map(AddressSpace *as, =20 if (!memory_access_is_direct(mr, is_write)) { if (atomic_xchg(&bounce.in_use, true)) { + *plen =3D 0; return NULL; } /* Avoid unbounded allocations */ diff --git a/include/exec/memory.h b/include/exec/memory.h index bd7fdd6081..af8ca7824e 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -2314,7 +2314,8 @@ bool address_space_access_valid(AddressSpace *as, hwa= ddr addr, hwaddr len, /* address_space_map: map a physical memory region into a host virtual add= ress * * May map a subset of the requested range, given by and returned in @plen. - * May return %NULL if resources needed to perform the mapping are exhaust= ed. + * May return %NULL and set *@plen to zero(0), if resources needed to perf= orm + * the mapping are exhausted. * Use only for reads OR writes - not for read-modify-write operations. * Use cpu_register_map_client() to know when retrying the map operation is * likely to succeed. --=20 2.26.2