Andrew Geissler | b7d2861 | 2020-07-24 16:15:54 -0500 | [diff] [blame] | 1 | From 77f55eac6c433e23e82a1b88b2d74f385c4c7d82 Mon Sep 17 00:00:00 2001 |
| 2 | From: Prasad J Pandit <pjp@fedoraproject.org> |
| 3 | Date: Tue, 26 May 2020 16:47:43 +0530 |
| 4 | Subject: [PATCH] exec: set map length to zero when returning NULL |
| 5 | MIME-Version: 1.0 |
| 6 | Content-Type: text/plain; charset=UTF-8 |
| 7 | Content-Transfer-Encoding: 8bit |
| 8 | |
| 9 | When mapping physical memory into host's virtual address space, |
| 10 | 'address_space_map' may return NULL if BounceBuffer is in_use. |
| 11 | Set and return '*plen = 0' to avoid later NULL pointer dereference. |
| 12 | |
| 13 | Reported-by: Alexander Bulekov <alxndr@bu.edu> |
| 14 | Fixes: https://bugs.launchpad.net/qemu/+bug/1878259 |
| 15 | Suggested-by: Paolo Bonzini <pbonzini@redhat.com> |
| 16 | Suggested-by: Peter Maydell <peter.maydell@linaro.org> |
| 17 | Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> |
| 18 | Message-Id: <20200526111743.428367-1-ppandit@redhat.com> |
| 19 | Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> |
| 20 | Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
| 21 | |
| 22 | Upstream-Status: Backport [77f55eac6c433e23e82a1b88b2d74f385c4c7d82] |
| 23 | CVE: CVE-2020-13659 |
| 24 | Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com> |
| 25 | --- |
| 26 | exec.c | 1 + |
| 27 | include/exec/memory.h | 3 ++- |
| 28 | 2 files changed, 3 insertions(+), 1 deletion(-) |
| 29 | |
| 30 | diff --git a/exec.c b/exec.c |
| 31 | index 9cbde85d8c..778263f1c6 100644 |
| 32 | --- a/exec.c |
| 33 | +++ b/exec.c |
| 34 | @@ -3540,6 +3540,7 @@ void *address_space_map(AddressSpace *as, |
| 35 | |
| 36 | if (!memory_access_is_direct(mr, is_write)) { |
| 37 | if (atomic_xchg(&bounce.in_use, true)) { |
| 38 | + *plen = 0; |
| 39 | return NULL; |
| 40 | } |
| 41 | /* Avoid unbounded allocations */ |
| 42 | diff --git a/include/exec/memory.h b/include/exec/memory.h |
| 43 | index bd7fdd6081..af8ca7824e 100644 |
| 44 | --- a/include/exec/memory.h |
| 45 | +++ b/include/exec/memory.h |
| 46 | @@ -2314,7 +2314,8 @@ bool address_space_access_valid(AddressSpace *as, hwaddr addr, hwaddr len, |
| 47 | /* address_space_map: map a physical memory region into a host virtual address |
| 48 | * |
| 49 | * May map a subset of the requested range, given by and returned in @plen. |
| 50 | - * May return %NULL if resources needed to perform the mapping are exhausted. |
| 51 | + * May return %NULL and set *@plen to zero(0), if resources needed to perform |
| 52 | + * the mapping are exhausted. |
| 53 | * Use only for reads OR writes - not for read-modify-write operations. |
| 54 | * Use cpu_register_map_client() to know when retrying the map operation is |
| 55 | * likely to succeed. |
| 56 | -- |
| 57 | 2.20.1 |
| 58 | |