| Message ID | 20200526111743.428367-1-ppandit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] exec: set map length to zero when returning NULL | expand |
On 5/26/20 1:17 PM, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > 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> > --- > exec.c | 1 + > include/exec/memory.h | 3 ++- > 2 files changed, 3 insertions(+), 1 deletion(-) > > Update v4: update address_space_map API doc text > -> https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg07281.html > > diff --git a/exec.c b/exec.c > index 5162f0d12f..4eea84bf66 100644 > --- a/exec.c > +++ b/exec.c > @@ -3538,6 +3538,7 @@ void *address_space_map(AddressSpace *as, > > if (!memory_access_is_direct(mr, is_write)) { > if (atomic_xchg(&bounce.in_use, true)) { > + *plen = 0; Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > return NULL; > } > /* Avoid unbounded allocations */ > diff --git a/include/exec/memory.h b/include/exec/memory.h > index e000bd2f97..8fa2d3cab2 100644 > --- a/include/exec/memory.h > +++ b/include/exec/memory.h > @@ -2303,7 +2303,8 @@ 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. >
On 26/05/20 13:17, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > 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> > --- > exec.c | 1 + > include/exec/memory.h | 3 ++- > 2 files changed, 3 insertions(+), 1 deletion(-) > > Update v4: update address_space_map API doc text > -> https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg07281.html > > diff --git a/exec.c b/exec.c > index 5162f0d12f..4eea84bf66 100644 > --- a/exec.c > +++ b/exec.c > @@ -3538,6 +3538,7 @@ 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 e000bd2f97..8fa2d3cab2 100644 > --- a/include/exec/memory.h > +++ b/include/exec/memory.h > @@ -2303,7 +2303,8 @@ 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. > Queued, thanks. Paolo
diff --git a/exec.c b/exec.c index 5162f0d12f..4eea84bf66 100644 --- a/exec.c +++ b/exec.c @@ -3538,6 +3538,7 @@ 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 e000bd2f97..8fa2d3cab2 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -2303,7 +2303,8 @@ 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.