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| Started by | Ben Hutchings <ben@decadent.org.uk> |
|---|---|
| First post | 2016-08-14 14:10 +0200 |
| Last post | 2016-08-14 14:10 +0200 |
| Articles | 1 — 1 participant |
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[PATCH 3.16 242/305] s390: fix test_fp_ctl inline assembly contraints Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
| From | Ben Hutchings <ben@decadent.org.uk> |
|---|---|
| Date | 2016-08-14 14:10 +0200 |
| Subject | [PATCH 3.16 242/305] s390: fix test_fp_ctl inline assembly contraints |
| Message-ID | <s62oP-7TC-51@gated-at.bofh.it> |
3.16.37-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Martin Schwidefsky <schwidefsky@de.ibm.com> commit bcf4dd5f9ee096bd1510f838dd4750c35df4e38b upstream. The test_fp_ctl function is used to test if a given value is a valid floating-point control. The inline assembly in test_fp_ctl uses an incorrect constraint for the 'orig_fpc' variable. If the compiler chooses the same register for 'fpc' and 'orig_fpc' the test_fp_ctl() function always returns true. This allows user space to trigger kernel oopses with invalid floating-point control values on the signal stack. This problem has been introduced with git commit 4725c86055f5bbdcdf "s390: fix save and restore of the floating-point-control register" Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- arch/s390/include/asm/switch_to.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/s390/include/asm/switch_to.h +++ b/arch/s390/include/asm/switch_to.h @@ -28,7 +28,7 @@ static inline int test_fp_ctl(u32 fpc) " la %0,0\n" "1:\n" EX_TABLE(0b,1b) - : "=d" (rc), "=d" (orig_fpc) + : "=d" (rc), "=&d" (orig_fpc) : "d" (fpc), "0" (-EINVAL)); return rc; }
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