From: "Eric W. Biederman" ebiederm@xmission.com
[ Upstream commit 7771c66457004977b616bab785209f49d164f527 ]
Setting si_code to 0 results in a userspace seeing an si_code of 0. This is the same si_code as SI_USER. Posix and common sense requires that SI_USER not be a signal specific si_code. As such this use of 0 for the si_code is a pretty horribly broken ABI.
Further use of si_code == 0 guaranteed that copy_siginfo_to_user saw a value of __SI_KILL and now sees a value of SIL_KILL with the result that uid and pid fields are copied and which might copying the si_addr field by accident but certainly not by design. Making this a very flakey implementation.
Utilizing FPE_FIXME, siginfo_layout will now return SIL_FAULT and the appropriate fields will be reliably copied.
Possible ABI fixes includee: - Send the signal without siginfo - Don't generate a signal - Possibly assign and use an appropriate si_code - Don't handle cases which can't happen
Cc: Russell King rmk@flint.arm.linux.org.uk Cc: linux-arm-kernel@lists.infradead.org Ref: 451436b7bbb2 ("[ARM] Add support code for ARM hardware vector floating point") History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/arm/include/uapi/asm/siginfo.h | 13 +++++++++++++ arch/arm/vfp/vfpmodule.c | 2 +- 2 files changed, 14 insertions(+), 1 deletion(-) create mode 100644 arch/arm/include/uapi/asm/siginfo.h
diff --git a/arch/arm/include/uapi/asm/siginfo.h b/arch/arm/include/uapi/asm/siginfo.h new file mode 100644 index 000000000000..d0513880be21 --- /dev/null +++ b/arch/arm/include/uapi/asm/siginfo.h @@ -0,0 +1,13 @@ +#ifndef __ASM_SIGINFO_H +#define __ASM_SIGINFO_H + +#include <asm-generic/siginfo.h> + +/* + * SIGFPE si_codes + */ +#ifdef __KERNEL__ +#define FPE_FIXME 0 /* Broken dup of SI_USER */ +#endif /* __KERNEL__ */ + +#endif diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index 2a61e4b04600..333b74b7fc02 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -261,7 +261,7 @@ static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_
if (exceptions == VFP_EXCEPTION_ERROR) { vfp_panic("unhandled bounce", inst); - vfp_raise_sigfpe(0, regs); + vfp_raise_sigfpe(FPE_FIXME, regs); return; }