On Mon, Nov 05, 2018 at 10:58:30PM +0000, Paul Burton wrote:
From: Huacai Chen <chenhc@xxxxxxxxxx>
[ Upstream commit c61c7def1fa0a722610d89790e0255b74f3c07dd ]
Commit ea7e0480a4b6 ("MIPS: VDSO: Always map near top of user memory")
set VDSO_RANDOMIZE_SIZE to 256MB for 64bit kernel. But take a look at
arch/mips/mm/mmap.c we can see that MIN_GAP is 128MB, which means the
mmap_base may be at (user_address_top - 128MB). This make the stack be
surrounded by mmaped areas, then stack expanding fails and causes a
segmentation fault. Therefore, VDSO_RANDOMIZE_SIZE should be less than
MIN_GAP and this patch reduce it to 64MB.
Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
Fixes: ea7e0480a4b6 ("MIPS: VDSO: Always map near top of user memory")
Patchwork: https://patchwork.linux-mips.org/patch/20910/
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: Fuxin Zhang <zhangfx@xxxxxxxxxx>
Cc: Zhangjin Wu <wuzhangjin@xxxxxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 4.19
Now queued for 4.19, thank you.
--
Thanks,
Sasha
