elf: Expose ELF header in compat_start_thread() (bc3d7bf6) · Commits · 戴 / test

Like it is done for SET_PERSONALITY with x86, which requires the ELF header to select correct personality parameters, x86 requires the headers on compat_start_thread() to choose starting CS for ELF32 binaries, instead of relying on the going-away TIF_IA32/X32 flags. Add an indirection macro to ELF invocations of START_THREAD, that x86 can reimplement to receive the extra parameter just for ELF files. This requires no changes to other architectures who don't need the header information, they can continue to use the original start_thread for ELF and non-ELF binaries, and it prevents affecting non-ELF code paths for x86. Signed-off-by:

Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20201004032536.1229030-6-krisman@collabora.com

fs/binfmt_elf.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1307,7 +1307,7 @@ out_free_interp:
		#endif

		finalize_exec(bprm);
		start_thread(regs, elf_entry, bprm->p);
		START_THREAD(elf_ex, regs, elf_entry, bprm->p);
		retval = 0;
		out:
		return retval;

fs/compat_binfmt_elf.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -106,8 +106,13 @@
		#endif

		#ifdef compat_start_thread
		#undef start_thread
		#define start_thread compat_start_thread
		#define COMPAT_START_THREAD(ex, regs, new_ip, new_sp) \
		compat_start_thread(regs, new_ip, new_sp)
		#endif

		#ifdef COMPAT_START_THREAD
		#undef START_THREAD
		#define START_THREAD COMPAT_START_THREAD
		#endif

		#ifdef compat_arch_setup_additional_pages

include/linux/elf.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -22,6 +22,11 @@
		SET_PERSONALITY(ex)
		#endif

		#ifndef START_THREAD
		#define START_THREAD(elf_ex, regs, elf_entry, start_stack) \
		start_thread(regs, elf_entry, start_stack)
		#endif

		#define ELF32_GNU_PROPERTY_ALIGN 4
		#define ELF64_GNU_PROPERTY_ALIGN 8

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