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authorSergey Bugaev <bugaevc@gmail.com>2023-06-26 02:17:48 +0300
committerSamuel Thibault <samuel.thibault@ens-lyon.org>2023-07-03 01:38:08 +0200
commit4b5e576fc21931969c0a1b53fdaf7ce3bfcebb86 (patch)
treed43ea87d74c802ee718b178c2138066a902dd204 /sysdeps/mach/hurd
parent019b0bbc84e2048556ac1a6b6df3a61e45fc1e17 (diff)
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hurd: Map brk non-executable
The rest of the heap (backed by individual pages) is already mapped RW.
Mapping these pages RWX presents a security hazard.

Also, in another branch memory gets allocated using vm_allocate, which
sets memory protection to VM_PROT_DEFAULT (which is RW). The mismatch
between protections prevents Mach from coalescing the VM map entries.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230625231751.404120-2-bugaevc@gmail.com>
Diffstat (limited to 'sysdeps/mach/hurd')
-rw-r--r--sysdeps/mach/hurd/brk.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/sysdeps/mach/hurd/brk.c b/sysdeps/mach/hurd/brk.c
index f1349495f5..3a335194f5 100644
--- a/sysdeps/mach/hurd/brk.c
+++ b/sysdeps/mach/hurd/brk.c
@@ -106,7 +106,7 @@ _hurd_set_brk (vm_address_t addr)
 	/* First finish allocation.  */
 	err = __vm_protect (__mach_task_self (), pagebrk,
 			    alloc_start - pagebrk, 0,
-			    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
+			    VM_PROT_READ|VM_PROT_WRITE);
       if (! err)
 	_hurd_brk = alloc_start;
 
@@ -120,7 +120,7 @@ _hurd_set_brk (vm_address_t addr)
   else
     /* Make the memory accessible.  */
     err = __vm_protect (__mach_task_self (), pagebrk, pagend - pagebrk,
-			0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
+			0, VM_PROT_READ|VM_PROT_WRITE);
 
   if (err)
     return __hurd_fail (err);