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| author | Chang S. Bae <chang.seok.bae@intel.com> | 2021-05-18 22:03:17 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-05-19 12:18:45 +0200 |
| commit | 1c33bb0507508af24fd754dd7123bd8e997fab2f (patch) | |
| tree | 0a245b44e47ae22c57669af809f34ff1d9549314 /arch/x86/include/asm/elf.h | |
| parent | x86/signal: Introduce helpers to get the maximum signal frame size (diff) | |
| download | linux-1c33bb0507508af24fd754dd7123bd8e997fab2f.tar.xz linux-1c33bb0507508af24fd754dd7123bd8e997fab2f.zip | |
x86/elf: Support a new ELF aux vector AT_MINSIGSTKSZ
Historically, signal.h defines MINSIGSTKSZ (2KB) and SIGSTKSZ (8KB), for
use by all architectures with sigaltstack(2). Over time, the hardware state
size grew, but these constants did not evolve. Today, literal use of these
constants on several architectures may result in signal stack overflow, and
thus user data corruption.
A few years ago, the ARM team addressed this issue by establishing
getauxval(AT_MINSIGSTKSZ). This enables the kernel to supply a value
at runtime that is an appropriate replacement on current and future
hardware.
Add getauxval(AT_MINSIGSTKSZ) support to x86, analogous to the support
added for ARM in
94b07c1f8c39 ("arm64: signal: Report signal frame size to userspace via auxv").
Also, include a documentation to describe x86-specific auxiliary vectors.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Len Brown <len.brown@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20210518200320.17239-4-chang.seok.bae@intel.com
Diffstat (limited to 'arch/x86/include/asm/elf.h')
| -rw-r--r-- | arch/x86/include/asm/elf.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 7d7500806af8..29fea180a665 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -312,6 +312,7 @@ do { \ NEW_AUX_ENT(AT_SYSINFO, VDSO_ENTRY); \ NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_CURRENT_BASE); \ } \ + NEW_AUX_ENT(AT_MINSIGSTKSZ, get_sigframe_size()); \ } while (0) /* @@ -328,6 +329,7 @@ extern unsigned long task_size_32bit(void); extern unsigned long task_size_64bit(int full_addr_space); extern unsigned long get_mmap_base(int is_legacy); extern bool mmap_address_hint_valid(unsigned long addr, unsigned long len); +extern unsigned long get_sigframe_size(void); #ifdef CONFIG_X86_32 @@ -349,6 +351,7 @@ do { \ if (vdso64_enabled) \ NEW_AUX_ENT(AT_SYSINFO_EHDR, \ (unsigned long __force)current->mm->context.vdso); \ + NEW_AUX_ENT(AT_MINSIGSTKSZ, get_sigframe_size()); \ } while (0) /* As a historical oddity, the x32 and x86_64 vDSOs are controlled together. */ @@ -357,6 +360,7 @@ do { \ if (vdso64_enabled) \ NEW_AUX_ENT(AT_SYSINFO_EHDR, \ (unsigned long __force)current->mm->context.vdso); \ + NEW_AUX_ENT(AT_MINSIGSTKSZ, get_sigframe_size()); \ } while (0) #define AT_SYSINFO 32 |