55 lines
2.2 KiB
Diff
55 lines
2.2 KiB
Diff
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From a1a9d6f908b21878daa7868313243c30b7a90fcf Mon Sep 17 00:00:00 2001
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From: Prasad J Pandit <pjp@fedoraproject.org>
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Date: Tue, 26 May 2020 16:47:43 +0530
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Subject: [PATCH 2/9] exec: set map length to zero when returning NULL
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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When mapping physical memory into host's virtual address space,
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'address_space_map' may return NULL if BounceBuffer is in_use.
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Set and return '*plen = 0' to avoid later NULL pointer dereference.
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Reported-by: Alexander Bulekov <alxndr@bu.edu>
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Fixes: https://bugs.launchpad.net/qemu/+bug/1878259
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Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
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Suggested-by: Peter Maydell <peter.maydell@linaro.org>
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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Message-Id: <20200526111743.428367-1-ppandit@redhat.com>
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Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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---
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exec.c | 1 +
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include/exec/memory.h | 3 ++-
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2 files changed, 3 insertions(+), 1 deletion(-)
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diff --git a/exec.c b/exec.c
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index 3e78de3b8f..85c6d80353 100644
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--- a/exec.c
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+++ b/exec.c
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@@ -3739,6 +3739,7 @@ void *address_space_map(AddressSpace *as,
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if (!memory_access_is_direct(mr, is_write)) {
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if (atomic_xchg(&bounce.in_use, true)) {
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rcu_read_unlock();
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+ *plen = 0;
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return NULL;
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}
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/* Avoid unbounded allocations */
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diff --git a/include/exec/memory.h b/include/exec/memory.h
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index 611a89122d..dca8184277 100644
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--- a/include/exec/memory.h
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+++ b/include/exec/memory.h
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@@ -2064,7 +2064,8 @@ bool address_space_access_valid(AddressSpace *as, hwaddr addr, hwaddr len,
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/* address_space_map: map a physical memory region into a host virtual address
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*
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* May map a subset of the requested range, given by and returned in @plen.
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- * May return %NULL if resources needed to perform the mapping are exhausted.
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+ * May return %NULL and set *@plen to zero(0), if resources needed to perform
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+ * the mapping are exhausted.
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* Use only for reads OR writes - not for read-modify-write operations.
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* Use cpu_register_map_client() to know when retrying the map operation is
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* likely to succeed.
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--
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2.25.1
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