| From 77f55eac6c433e23e82a1b88b2d74f385c4c7d82 Mon Sep 17 00:00:00 2001 |
| From: Prasad J Pandit <pjp@fedoraproject.org> |
| Date: Tue, 26 May 2020 16:47:43 +0530 |
| Subject: [PATCH] exec: set map length to zero when returning NULL |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| 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 = 0' to avoid later NULL pointer dereference. |
| |
| Reported-by: Alexander Bulekov <alxndr@bu.edu> |
| Fixes: https://bugs.launchpad.net/qemu/+bug/1878259 |
| Suggested-by: Paolo Bonzini <pbonzini@redhat.com> |
| Suggested-by: Peter Maydell <peter.maydell@linaro.org> |
| Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> |
| Message-Id: <20200526111743.428367-1-ppandit@redhat.com> |
| Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> |
| Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
| |
| Upstream-Status: Backport [77f55eac6c433e23e82a1b88b2d74f385c4c7d82] |
| CVE: CVE-2020-13659 |
| Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com> |
| --- |
| 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, |
| |
| if (!memory_access_is_direct(mr, is_write)) { |
| if (atomic_xchg(&bounce.in_use, true)) { |
| + *plen = 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, hwaddr addr, hwaddr len, |
| /* address_space_map: map a physical memory region into a host virtual address |
| * |
| * 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 exhausted. |
| + * May return %NULL and set *@plen to zero(0), if resources needed to perform |
| + * 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. |
| -- |
| 2.20.1 |
| |