As stated in the 1ad9f0a464fe commit log, the returned entries are not
a while PTEG. It was not a problem before 1ad9f0a464fe as it would read
a single record assuming it contains a whole PTEG but now the code tries
reading the entire PTEG and "if ((n - i) < invalid)" produces negative
values which then are converted to size_t for memset() and that throws
seg fault.
This fixes the math.
While here, fix the last @i increment as well.
Fixes: 1ad9f0a464fe "target/ppc: Fix KVM-HV HPTE accessors"
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Record #0:
(gdb) p *hdr
$13 = {
index = <ptr>,
n_valid = 0x1,
n_invalid = 0x6
}
Record #1:
(gdb) p *hdr
$18 = {
index = <ptr>,
n_valid = 0x2,
n_invalid = 0x6
}
i.e. in the second iteration of the loop right before
"if ((n - i) < invalid)":
(gdb) p n
$16 = 0x8
(gdb) p i
$17 = 0x9
and @invalid becomes -1.
---
target/ppc/kvm.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 0566af7..c2dea81 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -2657,21 +2657,24 @@ void kvmppc_read_hptes(ppc_hash_pte64_t *hptes, hwaddr ptex, int n)
hdr = (struct kvm_get_htab_header *)buf;
while ((i < n) && ((char *)hdr < (buf + rc))) {
- int invalid = hdr->n_invalid;
+ int invalid = hdr->n_invalid, valid = hdr->n_valid;
if (hdr->index != (ptex + i)) {
hw_error("kvmppc_read_hptes: Unexpected HPTE index %"PRIu32
" != (%"HWADDR_PRIu" + %d", hdr->index, ptex, i);
}
- memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * hdr->n_valid);
- i += hdr->n_valid;
+ if (n - i < valid) {
+ valid = n - i;
+ }
+ memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * valid);
+ i += valid;
if ((n - i) < invalid) {
invalid = n - i;
}
memset(hptes + i, 0, invalid * HASH_PTE_SIZE_64);
- i += hdr->n_invalid;
+ i += invalid;
hdr = (struct kvm_get_htab_header *)
((char *)(hdr + 1) + HASH_PTE_SIZE_64 * hdr->n_valid);
--
2.11.0
On Thu, Jan 11, 2018 at 03:08:32PM +1100, Alexey Kardashevskiy wrote: > As stated in the 1ad9f0a464fe commit log, the returned entries are not > a while PTEG. It was not a problem before 1ad9f0a464fe as it would read > a single record assuming it contains a whole PTEG but now the code tries > reading the entire PTEG and "if ((n - i) < invalid)" produces negative > values which then are converted to size_t for memset() and that throws > seg fault. > > This fixes the math. > > While here, fix the last @i increment as well. > > Fixes: 1ad9f0a464fe "target/ppc: Fix KVM-HV HPTE accessors" > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Applied, thanks. > --- > > Record #0: > (gdb) p *hdr > $13 = { > index = <ptr>, > n_valid = 0x1, > n_invalid = 0x6 > } > > Record #1: > (gdb) p *hdr > $18 = { > index = <ptr>, > n_valid = 0x2, > n_invalid = 0x6 > } > > > i.e. in the second iteration of the loop right before > "if ((n - i) < invalid)": > (gdb) p n > $16 = 0x8 > (gdb) p i > $17 = 0x9 > > and @invalid becomes -1. > > --- > target/ppc/kvm.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index 0566af7..c2dea81 100644 > --- a/target/ppc/kvm.c > +++ b/target/ppc/kvm.c > @@ -2657,21 +2657,24 @@ void kvmppc_read_hptes(ppc_hash_pte64_t *hptes, hwaddr ptex, int n) > > hdr = (struct kvm_get_htab_header *)buf; > while ((i < n) && ((char *)hdr < (buf + rc))) { > - int invalid = hdr->n_invalid; > + int invalid = hdr->n_invalid, valid = hdr->n_valid; > > if (hdr->index != (ptex + i)) { > hw_error("kvmppc_read_hptes: Unexpected HPTE index %"PRIu32 > " != (%"HWADDR_PRIu" + %d", hdr->index, ptex, i); > } > > - memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * hdr->n_valid); > - i += hdr->n_valid; > + if (n - i < valid) { > + valid = n - i; > + } > + memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * valid); > + i += valid; > > if ((n - i) < invalid) { > invalid = n - i; > } > memset(hptes + i, 0, invalid * HASH_PTE_SIZE_64); > - i += hdr->n_invalid; > + i += invalid; > > hdr = (struct kvm_get_htab_header *) > ((char *)(hdr + 1) + HASH_PTE_SIZE_64 * hdr->n_valid); -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
On 11/01/18 04:08, Alexey Kardashevskiy wrote: > As stated in the 1ad9f0a464fe commit log, the returned entries are not > a while PTEG. It was not a problem before 1ad9f0a464fe as it would read s/while/whole/? > a single record assuming it contains a whole PTEG but now the code tries > reading the entire PTEG and "if ((n - i) < invalid)" produces negative > values which then are converted to size_t for memset() and that throws > seg fault. > > This fixes the math. > > While here, fix the last @i increment as well. > > Fixes: 1ad9f0a464fe "target/ppc: Fix KVM-HV HPTE accessors" > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > --- > > Record #0: > (gdb) p *hdr > $13 = { > index = <ptr>, > n_valid = 0x1, > n_invalid = 0x6 > } > > Record #1: > (gdb) p *hdr > $18 = { > index = <ptr>, > n_valid = 0x2, > n_invalid = 0x6 > } > > > i.e. in the second iteration of the loop right before > "if ((n - i) < invalid)": > (gdb) p n > $16 = 0x8 > (gdb) p i > $17 = 0x9 > > and @invalid becomes -1. > > --- > target/ppc/kvm.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index 0566af7..c2dea81 100644 > --- a/target/ppc/kvm.c > +++ b/target/ppc/kvm.c > @@ -2657,21 +2657,24 @@ void kvmppc_read_hptes(ppc_hash_pte64_t *hptes, hwaddr ptex, int n) > > hdr = (struct kvm_get_htab_header *)buf; > while ((i < n) && ((char *)hdr < (buf + rc))) { > - int invalid = hdr->n_invalid; > + int invalid = hdr->n_invalid, valid = hdr->n_valid; > > if (hdr->index != (ptex + i)) { > hw_error("kvmppc_read_hptes: Unexpected HPTE index %"PRIu32 > " != (%"HWADDR_PRIu" + %d", hdr->index, ptex, i); > } > > - memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * hdr->n_valid); > - i += hdr->n_valid; > + if (n - i < valid) { > + valid = n - i; > + } > + memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * valid); > + i += valid; > > if ((n - i) < invalid) { > invalid = n - i; > } > memset(hptes + i, 0, invalid * HASH_PTE_SIZE_64); > - i += hdr->n_invalid; > + i += invalid; > > hdr = (struct kvm_get_htab_header *) > ((char *)(hdr + 1) + HASH_PTE_SIZE_64 * hdr->n_valid); > ATB, Mark.
On Thu, Jan 11, 2018 at 08:06:13AM +0000, Mark Cave-Ayland wrote: > On 11/01/18 04:08, Alexey Kardashevskiy wrote: > > > As stated in the 1ad9f0a464fe commit log, the returned entries are not > > a while PTEG. It was not a problem before 1ad9f0a464fe as it would read > > s/while/whole/? I already merged, so I adjusted this in my tree. Come to that although the fix is correct, I don't think the current message explains it very well. I'll think about adjusting it. > > > a single record assuming it contains a whole PTEG but now the code tries > > reading the entire PTEG and "if ((n - i) < invalid)" produces negative > > values which then are converted to size_t for memset() and that throws > > seg fault. > > > > This fixes the math. > > > > While here, fix the last @i increment as well. > > > > Fixes: 1ad9f0a464fe "target/ppc: Fix KVM-HV HPTE accessors" > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> > > --- > > > > Record #0: > > (gdb) p *hdr > > $13 = { > > index = <ptr>, > > n_valid = 0x1, > > n_invalid = 0x6 > > } > > > > Record #1: > > (gdb) p *hdr > > $18 = { > > index = <ptr>, > > n_valid = 0x2, > > n_invalid = 0x6 > > } > > > > > > i.e. in the second iteration of the loop right before > > "if ((n - i) < invalid)": > > (gdb) p n > > $16 = 0x8 > > (gdb) p i > > $17 = 0x9 > > > > and @invalid becomes -1. > > > > --- > > target/ppc/kvm.c | 11 +++++++---- > > 1 file changed, 7 insertions(+), 4 deletions(-) > > > > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > > index 0566af7..c2dea81 100644 > > --- a/target/ppc/kvm.c > > +++ b/target/ppc/kvm.c > > @@ -2657,21 +2657,24 @@ void kvmppc_read_hptes(ppc_hash_pte64_t *hptes, hwaddr ptex, int n) > > hdr = (struct kvm_get_htab_header *)buf; > > while ((i < n) && ((char *)hdr < (buf + rc))) { > > - int invalid = hdr->n_invalid; > > + int invalid = hdr->n_invalid, valid = hdr->n_valid; > > if (hdr->index != (ptex + i)) { > > hw_error("kvmppc_read_hptes: Unexpected HPTE index %"PRIu32 > > " != (%"HWADDR_PRIu" + %d", hdr->index, ptex, i); > > } > > - memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * hdr->n_valid); > > - i += hdr->n_valid; > > + if (n - i < valid) { > > + valid = n - i; > > + } > > + memcpy(hptes + i, hdr + 1, HASH_PTE_SIZE_64 * valid); > > + i += valid; > > if ((n - i) < invalid) { > > invalid = n - i; > > } > > memset(hptes + i, 0, invalid * HASH_PTE_SIZE_64); > > - i += hdr->n_invalid; > > + i += invalid; > > hdr = (struct kvm_get_htab_header *) > > ((char *)(hdr + 1) + HASH_PTE_SIZE_64 * hdr->n_valid); > > > > > ATB, > > Mark. > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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