Messages in this thread Patch in this message | | | From | Gabriel Krisman Bertazi <> | Subject | [PATCH v3 02/10] x86: Simplify compat syscall userspace allocation | Date | Sat, 3 Oct 2020 23:25:28 -0400 |
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When allocating user memory space for a compat system call, don't consider whether the originating code is IA32 or X32, just allocate from a safe region for both, beyond the redzone. This should be safe for IA32, and has the benefit of avoiding TIF_IA32, which we want to drop.
Suggested-by: Andy Lutomirski <luto@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> --- arch/x86/include/asm/compat.h | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h index d4edf281fff4..a4b5126dff4e 100644 --- a/arch/x86/include/asm/compat.h +++ b/arch/x86/include/asm/compat.h @@ -179,14 +179,13 @@ typedef struct user_regs_struct compat_elf_gregset_t; static inline void __user *arch_compat_alloc_user_space(long len) { - compat_uptr_t sp; - - if (test_thread_flag(TIF_IA32)) { - sp = task_pt_regs(current)->sp; - } else { - /* -128 for the x32 ABI redzone */ - sp = task_pt_regs(current)->sp - 128; - } + compat_uptr_t sp = task_pt_regs(current)->sp; + + /* + * -128 for the x32 ABI redzone. For IA32, it is not strictly + * necessary, but not harmful. + */ + sp -= 128; return (void __user *)round_down(sp - len, 16); } -- 2.28.0
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