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authorHeiko Carstens <heiko.carstens@de.ibm.com>2014-10-27 08:28:08 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2014-10-27 13:27:02 +0100
commit9b2efe035eafb1a29ff3dfe21ed0e755aac09130 (patch)
tree37f0a0c357aaf7305ca9acf2850c78da576c4f93 /arch/s390/kernel/vdso64
parent1f759bb3a2a0d75ceeeec729b1c66a7f443631ba (diff)
s390/vdso: fix stack corruption
The kernel provided vdso functions do not get a stack frame from the calling function and therefore may not change the stack contents, unless they allocate space on their own. This problem was exposed with 070b7be633dc "s390/vdso: replace stck with stcke" which writes 16 bytes instead of 8 bytes into the stack frame. These additional 8 bytes however were indeed used by the caller (glibc) to save data and therefore this data was corrupted by the vdso code. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/vdso64')
-rw-r--r--arch/s390/kernel/vdso64/clock_gettime.S13
-rw-r--r--arch/s390/kernel/vdso64/gettimeofday.S6
2 files changed, 13 insertions, 6 deletions
diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S
index 9d9761f8e110..7699e735ae28 100644
--- a/arch/s390/kernel/vdso64/clock_gettime.S
+++ b/arch/s390/kernel/vdso64/clock_gettime.S
@@ -19,6 +19,7 @@
.type __kernel_clock_gettime,@function
__kernel_clock_gettime:
.cfi_startproc
+ aghi %r15,-16
larl %r5,_vdso_data
cghi %r2,__CLOCK_REALTIME_COARSE
je 4f
@@ -37,10 +38,10 @@ __kernel_clock_gettime:
0: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
tmll %r4,0x0001 /* pending update ? loop */
jnz 0b
- stcke 48(%r15) /* Store TOD clock */
+ stcke 0(%r15) /* Store TOD clock */
lgf %r2,__VDSO_TK_SHIFT(%r5) /* Timekeeper shift */
lg %r0,__VDSO_WTOM_SEC(%r5)
- lg %r1,49(%r15)
+ lg %r1,1(%r15)
sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
msgf %r1,__VDSO_TK_MULT(%r5) /* * tk->mult */
alg %r1,__VDSO_WTOM_NSEC(%r5)
@@ -56,6 +57,7 @@ __kernel_clock_gettime:
2: stg %r0,0(%r3) /* store tp->tv_sec */
stg %r1,8(%r3) /* store tp->tv_nsec */
lghi %r2,0
+ aghi %r15,16
br %r14
/* CLOCK_MONOTONIC_COARSE */
@@ -82,9 +84,9 @@ __kernel_clock_gettime:
5: lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
tmll %r4,0x0001 /* pending update ? loop */
jnz 5b
- stcke 48(%r15) /* Store TOD clock */
+ stcke 0(%r15) /* Store TOD clock */
lgf %r2,__VDSO_TK_SHIFT(%r5) /* Timekeeper shift */
- lg %r1,49(%r15)
+ lg %r1,1(%r15)
sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
msgf %r1,__VDSO_TK_MULT(%r5) /* * tk->mult */
alg %r1,__VDSO_XTIME_NSEC(%r5) /* + tk->xtime_nsec */
@@ -101,6 +103,7 @@ __kernel_clock_gettime:
7: stg %r0,0(%r3) /* store tp->tv_sec */
stg %r1,8(%r3) /* store tp->tv_nsec */
lghi %r2,0
+ aghi %r15,16
br %r14
/* CLOCK_THREAD_CPUTIME_ID for this thread */
@@ -134,11 +137,13 @@ __kernel_clock_gettime:
slgr %r4,%r0 /* r4 = tv_nsec */
stg %r4,8(%r3)
lghi %r2,0
+ aghi %r15,16
br %r14
/* Fallback to system call */
12: lghi %r1,__NR_clock_gettime
svc 0
+ aghi %r15,16
br %r14
13: .quad 1000000000
diff --git a/arch/s390/kernel/vdso64/gettimeofday.S b/arch/s390/kernel/vdso64/gettimeofday.S
index 7a344995a97f..6ce46707663c 100644
--- a/arch/s390/kernel/vdso64/gettimeofday.S
+++ b/arch/s390/kernel/vdso64/gettimeofday.S
@@ -19,6 +19,7 @@
.type __kernel_gettimeofday,@function
__kernel_gettimeofday:
.cfi_startproc
+ aghi %r15,-16
larl %r5,_vdso_data
0: ltgr %r3,%r3 /* check if tz is NULL */
je 1f
@@ -28,8 +29,8 @@ __kernel_gettimeofday:
lg %r4,__VDSO_UPD_COUNT(%r5) /* load update counter */
tmll %r4,0x0001 /* pending update ? loop */
jnz 0b
- stcke 48(%r15) /* Store TOD clock */
- lg %r1,49(%r15)
+ stcke 0(%r15) /* Store TOD clock */
+ lg %r1,1(%r15)
sg %r1,__VDSO_XTIME_STAMP(%r5) /* TOD - cycle_last */
msgf %r1,__VDSO_TK_MULT(%r5) /* * tk->mult */
alg %r1,__VDSO_XTIME_NSEC(%r5) /* + tk->xtime_nsec */
@@ -50,6 +51,7 @@ __kernel_gettimeofday:
srlg %r0,%r0,6
stg %r0,8(%r2) /* store tv->tv_usec */
4: lghi %r2,0
+ aghi %r15,16
br %r14
5: .quad 1000000000
.long 274877907