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authorEelco Dolstra <eelco.dolstra@logicblox.com>2015-10-21T12·45+0200
committerEelco Dolstra <eelco.dolstra@logicblox.com>2015-10-21T13·14+0200
commit357d31b33962fcd19f2f05bd6ce6b8c7088a6e39 (patch)
tree26119b3cf98b9c762d1f55f632a16218c4c16e80 /src/libstore/build.cc
parent133a421bb40cca3a74c93b05f3abe310110c6258 (diff)
Fix segfault in builtin fetchurl
The stack allocated for the builder was way too small (32 KB). This is
sufficient for normal derivations, because they just do some setup and
then exec() the actual builder. But for the fetchurl builtin
derivation it's not enough. Also, allocating the stack on the caller's
stack was fishy business.
Diffstat (limited to 'src/libstore/build.cc')
-rw-r--r--src/libstore/build.cc10
1 files changed, 7 insertions, 3 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 5674e83c9e66..cb14c83b3a98 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -74,6 +74,7 @@
 
 #if __linux__
 #include <sys/personality.h>
+#include <sys/mman.h>
 #endif
 
 #if HAVE_STATVFS
@@ -2128,14 +2129,17 @@ void DerivationGoal::startBuilder()
         ProcessOptions options;
         options.allowVfork = false;
         Pid helper = startProcess([&]() {
-            char stack[32 * 1024];
+            size_t stackSize = 1 * 1024 * 1024;
+            char * stack = (char *) mmap(0, stackSize,
+                PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+            if (!stack) throw SysError("allocating stack");
             int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | CLONE_NEWUTS | CLONE_PARENT | SIGCHLD;
             if (!fixedOutput) flags |= CLONE_NEWNET;
-            pid_t child = clone(childEntry, stack + sizeof(stack) - 8, flags, this);
+            pid_t child = clone(childEntry, stack + stackSize, flags, this);
             if (child == -1 && errno == EINVAL)
                 /* Fallback for Linux < 2.13 where CLONE_NEWPID and
                    CLONE_PARENT are not allowed together. */
-                child = clone(childEntry, stack + sizeof(stack) - 8, flags & ~CLONE_NEWPID, this);
+                child = clone(childEntry, stack + stackSize, flags & ~CLONE_NEWPID, this);
             if (child == -1) throw SysError("cloning builder process");
             writeFull(builderOut.writeSide, int2String(child) + "\n");
             _exit(0);