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Don't directly access userspace memory.

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Rather then using the racy useracc() followed by direct access to
userspace memory, perform a copyin() and use the result if it succeeds.

Reviewed by:	jhb
MFC after:	3 weeks
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D24410
This commit is contained in:
Brooks Davis 2020-04-15 16:33:27 +00:00
parent 3e58608634
commit d0fa673e4d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=359974
1 changed files with 10 additions and 11 deletions
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21
sys/mips/mips/trap.c
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@ -1402,7 +1402,7 @@ log_illegal_instruction(const char *msg, struct trapframe *frame)
{
pt_entry_t *ptep;
pd_entry_t *pdep;
unsigned int *addr;
unsigned int *addr, instr[4];
struct thread *td;
struct proc *p;
register_t pc;
@ -1429,17 +1429,16 @@ log_illegal_instruction(const char *msg, struct trapframe *frame)
* Dump a few words around faulting instruction, if the addres is
* valid.
*/
if (!(pc & 3) &&
useracc((caddr_t)(intptr_t)pc, sizeof(int) * 4, VM_PROT_READ)) {
addr = (unsigned int *)(intptr_t)pc;
if ((pc & 3) == 0 && copyin(addr, instr, sizeof(instr)) == 0) {
/* dump page table entry for faulting instruction */
log(LOG_ERR, "Page table info for pc address %#jx: pde = %p, pte = %#jx\n",
(intmax_t)pc, (void *)(intptr_t)*pdep, (uintmax_t)(ptep ? *ptep : 0));
addr = (unsigned int *)(intptr_t)pc;
log(LOG_ERR, "Dumping 4 words starting at pc address %p: \n",
addr);
log(LOG_ERR, "%08x %08x %08x %08x\n",
addr[0], addr[1], addr[2], addr[3]);
instr[0], instr[1], instr[2], instr[3]);
} else {
log(LOG_ERR, "pc address %#jx is inaccessible, pde = %p, pte = %#jx\n",
(intmax_t)pc, (void *)(intptr_t)*pdep, (uintmax_t)(ptep ? *ptep : 0));
@ -1451,7 +1450,7 @@ log_bad_page_fault(char *msg, struct trapframe *frame, int trap_type)
{
pt_entry_t *ptep;
pd_entry_t *pdep;
unsigned int *addr;
unsigned int *addr, instr[4];
struct thread *td;
struct proc *p;
char *read_or_write;
@ -1499,18 +1498,18 @@ log_bad_page_fault(char *msg, struct trapframe *frame, int trap_type)
* Dump a few words around faulting instruction, if the addres is
* valid.
*/
if (!(pc & 3) && (pc != frame->badvaddr) &&
(trap_type != T_BUS_ERR_IFETCH) &&
useracc((caddr_t)(intptr_t)pc, sizeof(int) * 4, VM_PROT_READ)) {
addr = (unsigned int *)(intptr_t)pc;
if ((pc & 3) == 0 && pc != frame->badvaddr &&
trap_type != T_BUS_ERR_IFETCH &&
copyin((caddr_t)(intptr_t)pc, instr, sizeof(instr)) == 0) {
/* dump page table entry for faulting instruction */
log(LOG_ERR, "Page table info for pc address %#jx: pde = %p, pte = %#jx\n",
(intmax_t)pc, (void *)(intptr_t)*pdep, (uintmax_t)(ptep ? *ptep : 0));
addr = (unsigned int *)(intptr_t)pc;
log(LOG_ERR, "Dumping 4 words starting at pc address %p: \n",
addr);
log(LOG_ERR, "%08x %08x %08x %08x\n",
addr[0], addr[1], addr[2], addr[3]);
instr[0], instr[1], instr[2], instr[3]);
} else {
log(LOG_ERR, "pc address %#jx is inaccessible, pde = %p, pte = %#jx\n",
(intmax_t)pc, (void *)(intptr_t)*pdep, (uintmax_t)(ptep ? *ptep : 0));