Applied, thanks!
Sergey Bugaev, le lun. 26 juin 2023 02:17:50 +0300, a ecrit:
> Zero address passed to mmap () typically means the caller doesn't have
> any specific preferred address. Not so if MAP_FIXED is passed: in this
> case 0 means literal 0. Fix this case to pass anywhere = 0 into vm_map.
>
> Also add some documentation.
>
> Signed-off-by: Sergey Bugaev <buga...@gmail.com>
> ---
> sysdeps/mach/hurd/mmap.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/mach/hurd/mmap.c b/sysdeps/mach/hurd/mmap.c
> index 5aa70083..33672cf6 100644
> --- a/sysdeps/mach/hurd/mmap.c
> +++ b/sysdeps/mach/hurd/mmap.c
> @@ -38,7 +38,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int
> fd, off_t offset)
> vm_prot_t vmprot, max_vmprot;
> memory_object_t memobj;
> vm_address_t mapaddr, mask;
> - boolean_t copy;
> + boolean_t copy, anywhere;
>
> mapaddr = (vm_address_t) addr;
>
> @@ -55,6 +55,7 @@ __mmap (void *addr, size_t len, int prot, int flags, int
> fd, off_t offset)
> vmprot |= VM_PROT_EXECUTE;
>
> copy = ! (flags & MAP_SHARED);
> + anywhere = ! (flags & MAP_FIXED);
>
> #ifdef __LP64__
> if ((addr == NULL) && (prot & PROT_EXEC)
> @@ -141,9 +142,12 @@ __mmap (void *addr, size_t len, int prot, int flags, int
> fd, off_t offset)
> if (copy)
> max_vmprot = VM_PROT_ALL;
>
> + /* When ANYWHERE is true but the caller has provided a preferred address,
> + try mapping at that address with anywhere = 0 first. If this fails,
> + we'll retry with anywhere = 1 below. */
> err = __vm_map (__mach_task_self (),
> &mapaddr, (vm_size_t) len, mask,
> - mapaddr == 0,
> + anywhere && (mapaddr == 0),
> memobj, (vm_offset_t) offset,
> copy, vmprot, max_vmprot,
> copy ? VM_INHERIT_COPY : VM_INHERIT_SHARE);
> @@ -165,7 +169,10 @@ __mmap (void *addr, size_t len, int prot, int flags, int
> fd, off_t offset)
> }
> else
> {
> + /* This mmap call is allowed to allocate anywhere, */
> if (mapaddr != 0 && (err == KERN_NO_SPACE || err ==
> KERN_INVALID_ADDRESS))
> + /* ...but above, we tried allocating at the specific address,
> + and failed to. Now try again, with anywhere = 1 this time. */
> err = __vm_map (__mach_task_self (),
> &mapaddr, (vm_size_t) len, mask,
> 1, memobj, (vm_offset_t) offset,
> --
> 2.41.0
>
>
--
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.
