From 859d880cf544dbe095ce97534ef04cd88ba2f2b4 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 6 Mar 2018 00:20:25 -0600 Subject: [PATCH 1/3] signal: Correct the offset of si_pkey in struct siginfo The change moving addr_lsb into the _sigfault union failed to take into account that _sigfault._addr_bnd._lower being a pointer forced the entire union to have pointer alignment. In practice this only mattered for the offset of si_pkey which is why this has taken so long to discover. To correct this change _dummy_pkey and _dummy_bnd to have pointer type. Reported-by: kernel test robot Fixes: b68a68d3dcc1 ("signal: Move addr_lsb into the _sigfault union for clarity") Signed-off-by: "Eric W. Biederman" --- include/linux/compat.h | 4 ++-- include/uapi/asm-generic/siginfo.h | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index 8a9643857c4a..e16d07eb08cf 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -229,13 +229,13 @@ typedef struct compat_siginfo { short int _addr_lsb; /* Valid LSB of the reported address. */ /* used when si_code=SEGV_BNDERR */ struct { - short _dummy_bnd; + compat_uptr_t _dummy_bnd; compat_uptr_t _lower; compat_uptr_t _upper; } _addr_bnd; /* used when si_code=SEGV_PKUERR */ struct { - short _dummy_pkey; + compat_uptr_t _dummy_pkey; u32 _pkey; } _addr_pkey; }; diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h index 85dc965afd89..99c902e460c2 100644 --- a/include/uapi/asm-generic/siginfo.h +++ b/include/uapi/asm-generic/siginfo.h @@ -102,13 +102,13 @@ typedef struct siginfo { short _addr_lsb; /* LSB of the reported address */ /* used when si_code=SEGV_BNDERR */ struct { - short _dummy_bnd; + void *_dummy_bnd; void __user *_lower; void __user *_upper; } _addr_bnd; /* used when si_code=SEGV_PKUERR */ struct { - short _dummy_pkey; + void *_dummy_pkey; __u32 _pkey; } _addr_pkey; }; From f6a015498dcaee72f80283cb7873d88deb07129c Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 6 Mar 2018 00:29:17 -0600 Subject: [PATCH 2/3] signal/x86: Include the field offsets in the build time checks Due to an oversight when refactoring siginfo_t si_pkey has been in the wrong position since 4.16-rc1. Add an explicit check of the offset of every user space field in siginfo_t and compat_siginfo_t to make a mistake like this hard to make in the future. I have run this code on 4.15 and 4.16-rc1 with the position of si_pkey fixed and all of the fields show up in the same location. Signed-off-by: "Eric W. Biederman" --- arch/x86/kernel/signal_compat.c | 65 +++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c index ac057f9b0763..0d930d8987cc 100644 --- a/arch/x86/kernel/signal_compat.c +++ b/arch/x86/kernel/signal_compat.c @@ -43,6 +43,13 @@ static inline void signal_compat_build_tests(void) BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int)); #define CHECK_CSI_OFFSET(name) BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name)) + BUILD_BUG_ON(offsetof(siginfo_t, si_signo) != 0); + BUILD_BUG_ON(offsetof(siginfo_t, si_errno) != 4); + BUILD_BUG_ON(offsetof(siginfo_t, si_code) != 8); + + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_signo) != 0); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_errno) != 4); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_code) != 8); /* * Ensure that the size of each si_field never changes. * If it does, it is a sign that the @@ -63,36 +70,94 @@ static inline void signal_compat_build_tests(void) CHECK_CSI_SIZE (_kill, 2*sizeof(int)); CHECK_SI_SIZE (_kill, 2*sizeof(int)); + BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0xC); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); + CHECK_CSI_OFFSET(_timer); CHECK_CSI_SIZE (_timer, 3*sizeof(int)); CHECK_SI_SIZE (_timer, 6*sizeof(int)); + BUILD_BUG_ON(offsetof(siginfo_t, si_tid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_overrun) != 0x14); + BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_tid) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_overrun) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14); + CHECK_CSI_OFFSET(_rt); CHECK_CSI_SIZE (_rt, 3*sizeof(int)); CHECK_SI_SIZE (_rt, 4*sizeof(int)); + BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); + BUILD_BUG_ON(offsetof(siginfo_t, si_value) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_value) != 0x14); + CHECK_CSI_OFFSET(_sigchld); CHECK_CSI_SIZE (_sigchld, 5*sizeof(int)); CHECK_SI_SIZE (_sigchld, 8*sizeof(int)); + BUILD_BUG_ON(offsetof(siginfo_t, si_pid) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_uid) != 0x14); + BUILD_BUG_ON(offsetof(siginfo_t, si_status) != 0x18); + BUILD_BUG_ON(offsetof(siginfo_t, si_utime) != 0x20); + BUILD_BUG_ON(offsetof(siginfo_t, si_stime) != 0x28); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pid) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_uid) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_status) != 0x14); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_utime) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_stime) != 0x1C); + #ifdef CONFIG_X86_X32_ABI CHECK_CSI_OFFSET(_sigchld_x32); CHECK_CSI_SIZE (_sigchld_x32, 7*sizeof(int)); /* no _sigchld_x32 in the generic siginfo_t */ + BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime) != 0x20); #endif CHECK_CSI_OFFSET(_sigfault); CHECK_CSI_SIZE (_sigfault, 4*sizeof(int)); CHECK_SI_SIZE (_sigfault, 8*sizeof(int)); + BUILD_BUG_ON(offsetof(siginfo_t, si_addr) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr) != 0x0C); + + BUILD_BUG_ON(offsetof(siginfo_t, si_addr_lsb) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_addr_lsb) != 0x10); + + BUILD_BUG_ON(offsetof(siginfo_t, si_lower) != 0x20); + BUILD_BUG_ON(offsetof(siginfo_t, si_upper) != 0x28); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_lower) != 0x14); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_upper) != 0x18); + + BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14); + CHECK_CSI_OFFSET(_sigpoll); CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int)); CHECK_SI_SIZE (_sigpoll, 4*sizeof(int)); + BUILD_BUG_ON(offsetof(siginfo_t, si_band) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_fd) != 0x18); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_band) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_fd) != 0x10); + CHECK_CSI_OFFSET(_sigsys); CHECK_CSI_SIZE (_sigsys, 3*sizeof(int)); CHECK_SI_SIZE (_sigsys, 4*sizeof(int)); + BUILD_BUG_ON(offsetof(siginfo_t, si_call_addr) != 0x10); + BUILD_BUG_ON(offsetof(siginfo_t, si_syscall) != 0x18); + BUILD_BUG_ON(offsetof(siginfo_t, si_arch) != 0x1C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_call_addr) != 0x0C); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_syscall) != 0x10); + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_arch) != 0x14); + /* any new si_fields should be added here */ } From 266da65e9156d93e1126e185259a4aae68188d0e Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Thu, 1 Mar 2018 17:44:06 +0000 Subject: [PATCH 3/3] signal: Add FPE_FLTUNK si_code for undiagnosable fp exceptions Some architectures cannot always report accurately what kind of floating-point exception triggered a floating-point exception trap. This can occur with fp exceptions occurring on lanes in a vector instruction on arm64 for example. Rather than have every architecture come up with its own way of describing such a condition, this patch adds a common FPE_FLTUNK si_code value to report that an fp exception caused a trap but we cannot be certain which kind of fp exception it was. Signed-off-by: Dave Martin Signed-off-by: Eric W. Biederman --- arch/x86/kernel/signal_compat.c | 2 +- include/uapi/asm-generic/siginfo.h | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c index 0d930d8987cc..d2884e951bb5 100644 --- a/arch/x86/kernel/signal_compat.c +++ b/arch/x86/kernel/signal_compat.c @@ -26,7 +26,7 @@ static inline void signal_compat_build_tests(void) * new fields are handled in copy_siginfo_to_user32()! */ BUILD_BUG_ON(NSIGILL != 11); - BUILD_BUG_ON(NSIGFPE != 13); + BUILD_BUG_ON(NSIGFPE != 14); BUILD_BUG_ON(NSIGSEGV != 4); BUILD_BUG_ON(NSIGBUS != 5); BUILD_BUG_ON(NSIGTRAP != 4); diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h index 99c902e460c2..4b3520bf67ba 100644 --- a/include/uapi/asm-generic/siginfo.h +++ b/include/uapi/asm-generic/siginfo.h @@ -229,7 +229,8 @@ typedef struct siginfo { # define __FPE_INVASC 12 /* invalid ASCII digit */ # define __FPE_INVDEC 13 /* invalid decimal digit */ #endif -#define NSIGFPE 13 +#define FPE_FLTUNK 14 /* undiagnosed floating-point exception */ +#define NSIGFPE 14 /* * SIGSEGV si_codes