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authorMark H Weaver <mhw@netris.org>2017-08-07 16:41:03 -0400
committerMark H Weaver <mhw@netris.org>2017-08-07 16:41:03 -0400
commita1aa5dabaa5d570710da7190a3c3dca5442b9daa (patch)
treee19ba58b2535c3d838bd1cd5ee93636bfb4583fa /nix
parent73a203450d21241eca50375aeb26fb418b287414 (diff)
daemon: Ensure the child stack is aligned on a 16-byte boundary.
* nix/libstore/build.cc (DerivationGoal::startBuilder): When calling 'clone', ensure that the stack is aligned on a 16-byte boundary.
Diffstat (limited to 'nix')
-rw-r--r--nix/libstore/build.cc11
1 files changed, 6 insertions, 5 deletions
diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 693fa70c8d..63540ddfc1 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -26,6 +26,7 @@
#include <errno.h>
#include <stdio.h>
#include <cstring>
+#include <stdint.h>
#include <pwd.h>
#include <grp.h>
@@ -2008,11 +2009,11 @@ void DerivationGoal::startBuilder()
char stack[32 * 1024];
int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | CLONE_NEWUTS | SIGCHLD;
if (!fixedOutput) flags |= CLONE_NEWNET;
-#ifdef __aarch64__
- pid = clone(childEntry, stack + sizeof(stack) - 16, flags, this);
-#else
- pid = clone(childEntry, stack + sizeof(stack) - 8, flags, this);
-#endif
+ /* Ensure proper alignment on the stack. On aarch64, it has to be 16
+ bytes. */
+ pid = clone(childEntry,
+ (char *)(((uintptr_t)stack + sizeof(stack) - 8) & ~(uintptr_t)0xf),
+ flags, this);
if (pid == -1)
throw SysError("cloning builder process");
} else