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Change i386_get_ldt() to return 'EOF' when the requested range of

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descriptors does not fit into currently allocated LDT, or trim the
return if the range fits partially.  Before, the function returned
EINVAL.

Fix two bugs in r324366: use capped num counter for malloc size, and
do not leak allocated buffer on EINVAL (by handling EINVAL case as
normal, see above).

Reviewed by:	bde
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
kib 2017-10-09 16:19:26 +00:00
parent 3851626613
commit 8844e99855
1 changed files with 9 additions and 12 deletions
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21
sys/i386/i386/sys_machdep.c
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@ -534,23 +534,20 @@ i386_get_ldt(struct thread *td, struct i386_ldt_args *uap)
uap->start, uap->num, (void *)uap->descs);
#endif
if (uap->start >= MAX_LD)
return (EINVAL);
num = min(uap->num, MAX_LD - uap->start);
data = malloc(uap->num * sizeof(union descriptor), M_TEMP, M_WAITOK);
num = min(uap->num, MAX_LD);
data = malloc(num * sizeof(union descriptor), M_TEMP, M_WAITOK);
mtx_lock_spin(&dt_lock);
pldt = td->td_proc->p_md.md_ldt;
nldt = pldt != NULL ? pldt->ldt_len : nitems(ldt);
num = min(num, nldt);
if (uap->start > nldt || uap->start + num > nldt) {
mtx_unlock_spin(&dt_lock);
return (EINVAL);
if (uap->start >= nldt) {
num = 0;
} else {
num = min(num, nldt - uap->start);
bcopy(pldt != NULL ?
&((union descriptor *)(pldt->ldt_base))[uap->start] :
&ldt[uap->start], data, num * sizeof(union descriptor));
}
bcopy(pldt != NULL ?
&((union descriptor *)(pldt->ldt_base))[uap->start] :
&ldt[uap->start], data, num * sizeof(union descriptor));
mtx_unlock_spin(&dt_lock);
error = copyout(data, uap->descs, num * sizeof(union descriptor));
if (error == 0)
td->td_retval[0] = num;