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Subject[REVIEW][PATCH 02/17] sparc: fix compat siginfo ABI regression
From: "Dmitry V. Levin" <ldv@altlinux.org>

Starting with commit v4.14-rc1~60^2^2~1, a SIGFPE signal sent via kill
results to wrong values in si_pid and si_uid fields of compat siginfo_t.

This happens due to FPE_FIXME being defined to 0 for sparc, and at the
same time siginfo_layout() introduced by the same commit returns
SIL_FAULT for SIGFPE if si_code == SI_USER and FPE_FIXME is defined to 0.

Fix this regression by removing FPE_FIXME macro and changing all its users
to assign FPE_FLTUNK to si_code instead of FPE_FIXME.

Note that FPE_FLTUNK is a new macro introduced by commit
266da65e9156d93e1126e185259a4aae68188d0e.

Tested with commit v4.16-11958-g16e205cf42da.

This bug was found by strace test suite.

In the discussion about FPE_FLTUNK on sparc David Miller said:
> Eric, feel free to do something similar on Sparc.

Link: https://github.com/strace/strace/issues/21
Fixes: cc731525f26a ("signal: Remove kernel interal si_code magic")
Fixes: 2.3.41
Cc: David Miller <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
Conceptually-Acked-By: David Miller <davem@davemloft.net>
Thanks-to: Anatoly Pugachev <matorola@gmail.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
arch/sparc/include/uapi/asm/siginfo.h | 7 -------
arch/sparc/kernel/traps_32.c | 2 +-
arch/sparc/kernel/traps_64.c | 2 +-
3 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
index 896ce447d16a..e7049550ac82 100644
--- a/arch/sparc/include/uapi/asm/siginfo.h
+++ b/arch/sparc/include/uapi/asm/siginfo.h
@@ -17,13 +17,6 @@

#define SI_NOINFO 32767 /* no information in siginfo_t */

-/*
- * SIGFPE si_codes
- */
-#ifdef __KERNEL__
-#define FPE_FIXME 0 /* Broken dup of SI_USER */
-#endif /* __KERNEL__ */
-
/*
* SIGEMT si_codes
*/
diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c
index b1ed763e4787..33cd35bf3dc8 100644
--- a/arch/sparc/kernel/traps_32.c
+++ b/arch/sparc/kernel/traps_32.c
@@ -307,7 +307,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
info.si_errno = 0;
info.si_addr = (void __user *)pc;
info.si_trapno = 0;
- info.si_code = FPE_FIXME;
+ info.si_code = FPE_FLTUNK;
if ((fsr & 0x1c000) == (1 << 14)) {
if (fsr & 0x10)
info.si_code = FPE_FLTINV;
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index 462a21abd105..e81072ac52c3 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -2372,7 +2372,7 @@ static void do_fpe_common(struct pt_regs *regs)
info.si_errno = 0;
info.si_addr = (void __user *)regs->tpc;
info.si_trapno = 0;
- info.si_code = FPE_FIXME;
+ info.si_code = FPE_FLTUNK;
if ((fsr & 0x1c000) == (1 << 14)) {
if (fsr & 0x10)
info.si_code = FPE_FLTINV;
--
2.14.1
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