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x86/ptrace: make genregs[32]_get/set more robust

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The loop condition is fragile: we compare an unsigned value to zero, and
then decrement it by something larger than one in the loop.  All the
callers should be passing in appropriately aligned buffer lengths, but
it's better to just not rely on it, and have some appropriate defensive
loop limits.

Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2009-12-17 07:04:56 -08:00
parent 718deb6b61
commit 04a1e62c2c
1 changed files with 8 additions and 8 deletions
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16
arch/x86/kernel/ptrace.c
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@ -509,14 +509,14 @@ static int genregs_get(struct task_struct *target,
{ {
if (kbuf) { if (kbuf) {
unsigned long *k = kbuf; unsigned long *k = kbuf;
while (count > 0) { while (count >= sizeof(*k)) {
*k++ = getreg(target, pos); *k++ = getreg(target, pos);
count -= sizeof(*k); count -= sizeof(*k);
pos += sizeof(*k); pos += sizeof(*k);
} }
} else { } else {
unsigned long __user *u = ubuf; unsigned long __user *u = ubuf;
while (count > 0) { while (count >= sizeof(*u)) {
if (__put_user(getreg(target, pos), u++)) if (__put_user(getreg(target, pos), u++))
return -EFAULT; return -EFAULT;
count -= sizeof(*u); count -= sizeof(*u);
@ -535,14 +535,14 @@ static int genregs_set(struct task_struct *target,
int ret = 0; int ret = 0;
if (kbuf) { if (kbuf) {
const unsigned long *k = kbuf; const unsigned long *k = kbuf;
while (count > 0 && !ret) { while (count >= sizeof(*k) && !ret) {
ret = putreg(target, pos, *k++); ret = putreg(target, pos, *k++);
count -= sizeof(*k); count -= sizeof(*k);
pos += sizeof(*k); pos += sizeof(*k);
} }
} else { } else {
const unsigned long __user *u = ubuf; const unsigned long __user *u = ubuf;
while (count > 0 && !ret) { while (count >= sizeof(*u) && !ret) {
unsigned long word; unsigned long word;
ret = __get_user(word, u++); ret = __get_user(word, u++);
if (ret) if (ret)
@ -1458,14 +1458,14 @@ static int genregs32_get(struct task_struct *target,
{ {
if (kbuf) { if (kbuf) {
compat_ulong_t *k = kbuf; compat_ulong_t *k = kbuf;
while (count > 0) { while (count >= sizeof(*k)) {
getreg32(target, pos, k++); getreg32(target, pos, k++);
count -= sizeof(*k); count -= sizeof(*k);
pos += sizeof(*k); pos += sizeof(*k);
} }
} else { } else {
compat_ulong_t __user *u = ubuf; compat_ulong_t __user *u = ubuf;
while (count > 0) { while (count >= sizeof(*u)) {
compat_ulong_t word; compat_ulong_t word;
getreg32(target, pos, &word); getreg32(target, pos, &word);
if (__put_user(word, u++)) if (__put_user(word, u++))
@ -1486,14 +1486,14 @@ static int genregs32_set(struct task_struct *target,
int ret = 0; int ret = 0;
if (kbuf) { if (kbuf) {
const compat_ulong_t *k = kbuf; const compat_ulong_t *k = kbuf;
while (count > 0 && !ret) { while (count >= sizeof(*k) && !ret) {
ret = putreg32(target, pos, *k++); ret = putreg32(target, pos, *k++);
count -= sizeof(*k); count -= sizeof(*k);
pos += sizeof(*k); pos += sizeof(*k);
} }
} else { } else {
const compat_ulong_t __user *u = ubuf; const compat_ulong_t __user *u = ubuf;
while (count > 0 && !ret) { while (count >= sizeof(*u) && !ret) {
compat_ulong_t word; compat_ulong_t word;
ret = __get_user(word, u++); ret = __get_user(word, u++);
if (ret) if (ret)