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author | 2019-08-13 19:23:51 +0200 | |
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committer | 2019-08-21 12:58:53 +0200 | |
commit | 2c7fa8a11cc528e49e88352fce8cf083104b3797 (patch) | |
tree | 5bdb4f2c07e83410c0cdd0b299aed23e489fb3b3 /arch | |
parent | s390/process: avoid potential reading of freed stack (diff) | |
download | linux-2c7fa8a11cc528e49e88352fce8cf083104b3797.tar.gz linux-2c7fa8a11cc528e49e88352fce8cf083104b3797.tar.bz2 linux-2c7fa8a11cc528e49e88352fce8cf083104b3797.zip |
s390/kasan: avoid report in get_wchan
Reading other running task's stack can be a dangerous endeavor. Kasan
stack memory access instrumentation includes special prologue and epilogue
to mark/remove red zones in shadow memory between stack variables. For
that reason there is always a race between a task reading value in other
task's stack and that other task returning from a function and entering
another one generating different red zones pattern.
To avoid kasan reports simply perform uninstrumented memory reads.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/s390/kernel/process.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 9f2727bf3cbe..b0afec673f77 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -196,12 +196,12 @@ unsigned long get_wchan(struct task_struct *p) goto out; } for (count = 0; count < 16; count++) { - sf = (struct stack_frame *) sf->back_chain; + sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain); if (sf <= low || sf > high) { return_address = 0; goto out; } - return_address = sf->gprs[8]; + return_address = READ_ONCE_NOCHECK(sf->gprs[8]); if (!in_sched_functions(return_address)) goto out; } |