[PATCH] powerpc/vdso: Fix multiple issues with sys_call_table
From: Anton Blanchard <hidden>
Date: 2020-03-06 02:58:03
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
The VDSO exports a bitmap of valid syscalls. vdso_setup_syscall_map()
sets this up, but there are both little and big endian bugs. The issue
is with:
if (sys_call_table[i] != sys_ni_syscall)
On little endian, instead of comparing pointers to the two functions,
we compare the first two instructions of each function. If a function
happens to have the same first two instructions as sys_ni_syscall, then
we have a spurious match and mark the instruction as not implemented.
Fix this by removing the inline declarations.
On big endian we have a further issue where sys_ni_syscall is a function
descriptor and sys_call_table[] holds pointers to the instruction text.
Fix this by using dereference_kernel_function_descriptor().
Cc: stable@vger.kernel.org
Signed-off-by: Anton Blanchard <redacted>
---diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index b9a108411c0d..d186b729026e 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c@@ -17,6 +17,7 @@ #include <linux/elf.h> #include <linux/security.h> #include <linux/memblock.h> +#include <linux/syscalls.h> #include <asm/pgtable.h> #include <asm/processor.h>
@@ -30,6 +31,7 @@ #include <asm/vdso.h> #include <asm/vdso_datapage.h> #include <asm/setup.h> +#include <asm/syscall.h> #undef DEBUG
@@ -644,19 +646,16 @@ static __init int vdso_setup(void) static void __init vdso_setup_syscall_map(void) { unsigned int i; - extern unsigned long *sys_call_table; -#ifdef CONFIG_PPC64 - extern unsigned long *compat_sys_call_table; -#endif - extern unsigned long sys_ni_syscall; + unsigned long ni_syscall; + ni_syscall = (unsigned long)dereference_kernel_function_descriptor(sys_ni_syscall); for (i = 0; i < NR_syscalls; i++) { #ifdef CONFIG_PPC64 - if (sys_call_table[i] != sys_ni_syscall) + if (sys_call_table[i] != ni_syscall) vdso_data->syscall_map_64[i >> 5] |= 0x80000000UL >> (i & 0x1f); - if (compat_sys_call_table[i] != sys_ni_syscall) + if (compat_sys_call_table[i] != ni_syscall) vdso_data->syscall_map_32[i >> 5] |= 0x80000000UL >> (i & 0x1f); #else /* CONFIG_PPC64 */