diff options
| author | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2026-06-23 17:33:23 +0200 |
|---|---|---|
| committer | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2026-06-24 10:08:56 +0200 |
| commit | 7a386efcb2bf986e0c9011e92a78aed0870b08cf (patch) | |
| tree | 233093eb51cb8d00a2b00d99144df42b9793b8d7 | |
| parent | d4bb00704a66024502261fa7a523c07420249fea (diff) | |
KVM: s390: Fix dat_peek_cmma() overflow
If userspace passes a start address that is out of bounds,
_dat_walk_gfn_range() will fail with -EFAULT, but state.end will not be
touched and will stay 0. This will cause *count to underflow and report
a very high number, and the function will end up erroneously reporting
success.
Fix by only setting *count if the end address is not smaller than the
starting address. This way invalid starting addresses will correctly
return -EFAULT and *count will correctly indicate that no values have
been returned.
Fixes: 7b368470e1a4 ("KVM: s390: KVM page table management functions: CMMA")
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260623153331.233784-3-imbrenda@linux.ibm.com>
| -rw-r--r-- | arch/s390/kvm/dat.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c index 4a41c0247ffa..cffac7782c4b 100644 --- a/arch/s390/kvm/dat.c +++ b/arch/s390/kvm/dat.c @@ -1209,7 +1209,7 @@ int dat_peek_cmma(gfn_t start, union asce asce, unsigned int *count, u8 *values) int rc; rc = _dat_walk_gfn_range(start, start + *count, asce, &ops, DAT_WALK_DEFAULT, &state); - *count = state.end - start; + *count = state.end >= start ? state.end - start : 0; /* Return success if at least one value was saved, otherwise an error. */ return (rc == -EFAULT && *count > 0) ? 0 : rc; } |