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authorAnton Blanchard <anton@samba.org>2009-02-21 20:50:04 -0500
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-02-22 23:53:20 -0500
commit912f9ee21c836081e3c96dfe61025841ebeb95da (patch)
tree289e0c461cb651d041a2f1df359d88f285b82b4d /arch/powerpc/kernel/process.c
parentd839088caec6891a5070f0b1ce61031e458533a9 (diff)
powerpc: Randomise the brk region
Randomize the heap. before: tundro2:~ # sleep 1 & cat /proc/${!}/maps | grep heap 10017000-10118000 rw-p 10017000 00:00 0 [heap] 10017000-10118000 rw-p 10017000 00:00 0 [heap] 10017000-10118000 rw-p 10017000 00:00 0 [heap] 10017000-10118000 rw-p 10017000 00:00 0 [heap] 10017000-10118000 rw-p 10017000 00:00 0 [heap] after tundro2:~ # sleep 1 & cat /proc/${!}/maps | grep heap 19419000-1951a000 rw-p 19419000 00:00 0 [heap] 325ff000-32700000 rw-p 325ff000 00:00 0 [heap] 1a97c000-1aa7d000 rw-p 1a97c000 00:00 0 [heap] 1cc60000-1cd61000 rw-p 1cc60000 00:00 0 [heap] 1afa9000-1b0aa000 rw-p 1afa9000 00:00 0 [heap] Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/process.c')
-rw-r--r--arch/powerpc/kernel/process.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 69b9d2d3cb84..30b149ce7598 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1147,3 +1147,26 @@ unsigned long arch_align_stack(unsigned long sp)
1147 sp -= get_random_int() & ~PAGE_MASK; 1147 sp -= get_random_int() & ~PAGE_MASK;
1148 return sp & ~0xf; 1148 return sp & ~0xf;
1149} 1149}
1150
1151static inline unsigned long brk_rnd(void)
1152{
1153 unsigned long rnd = 0;
1154
1155 /* 8MB for 32bit, 1GB for 64bit */
1156 if (is_32bit_task())
1157 rnd = (long)(get_random_int() % (1<<(23-PAGE_SHIFT)));
1158 else
1159 rnd = (long)(get_random_int() % (1<<(30-PAGE_SHIFT)));
1160
1161 return rnd << PAGE_SHIFT;
1162}
1163
1164unsigned long arch_randomize_brk(struct mm_struct *mm)
1165{
1166 unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
1167
1168 if (ret < mm->brk)
1169 return mm->brk;
1170
1171 return ret;
1172}