AuroraMiddleware/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2024-12-25 12:11:10 +00:00
Code Issues Packages Projects Releases Wiki Activity

hurd: Fix x86_64 sigreturn restoring bogus reply_port

Browse Source 
Since the area of the user's stack we use for the registers dump (and
otherwise as __sigreturn2's stack) can and does overlap the sigcontext,
we have to be very careful about the order of loads and stores that we
do. In particular we have to load sc_reply_port before we start
clobbering the sigcontext.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
This commit is contained in:
Sergey Bugaev 2023-06-04 19:05:51 +02:00 committed by Samuel Thibault
parent 547de57e5a
commit 67f704ab69
1 changed files with 43 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
sysdeps/mach/hurd/x86_64/sigreturn.c
View File

@ -24,7 +24,7 @@
unlock SS off sigstack. */
void
__sigreturn2 (struct hurd_sigstate *ss, uintptr_t *usp,
struct sigcontext *scp)
mach_port_t sc_reply_port)
{
mach_port_t reply_port;
_hurd_sigstate_unlock (ss);
@ -44,7 +44,7 @@ __sigreturn2 (struct hurd_sigstate *ss, uintptr_t *usp,
if (__glibc_likely (MACH_PORT_VALID (reply_port)))
(void) __mach_port_mod_refs (__mach_task_self (), reply_port,
MACH_PORT_RIGHT_RECEIVE, -1);
THREAD_SETMEM (THREAD_SELF, reply_port, scp->sc_reply_port);
THREAD_SETMEM (THREAD_SELF, reply_port, sc_reply_port);
asm volatile (
/* Point the stack to the register dump. */
@ -77,6 +77,8 @@ __sigreturn (struct sigcontext *scp)
{
struct hurd_sigstate *ss;
struct hurd_userlink *link = (void *) &scp[1];
uintptr_t *usp;
mach_port_t sc_reply_port;
if (__glibc_unlikely (scp == NULL || (scp->sc_mask & _SIG_CANT_MASK)))
return __hurd_fail (EINVAL);
@ -118,42 +120,48 @@ __sigreturn (struct sigcontext *scp)
in the format the i387 `frstor' instruction uses to restore it. */
asm volatile ("frstor %0" : : "m" (scp->sc_fpsave));
{
/* There are convenient instructions to pop state off the stack, so we
copy the registers onto the user's stack, switch there, pop and
return. */
/* Copy the registers onto the user's stack, to be able to release the
altstack (by unlocking sigstate). Note that unless an altstack is used,
the sigcontext will itself be located on the user's stack, so we may well
be overwriting it here (or later in __sigreturn2).
uintptr_t *usp = (uintptr_t *) (scp->sc_ursp - 128);
So: do this very carefully. First, load sc_reply_port, which is the only
other bit of sigcontext that __sigreturn2 needs. Then copy the registers
without reordering them, but skipping the ones we won't need. We have to
copy starting from the larger addresses down, since our register dump is
located at a larger address than the sigcontext. */
*--usp = scp->sc_rip;
*--usp = scp->sc_rfl;
*--usp = scp->sc_rax;
*--usp = scp->sc_rcx;
*--usp = scp->sc_rdx;
*--usp = scp->sc_rbx;
*--usp = scp->sc_rbp;
*--usp = scp->sc_rsi;
*--usp = scp->sc_rdi;
*--usp = scp->sc_r15;
*--usp = scp->sc_r14;
*--usp = scp->sc_r13;
*--usp = scp->sc_r12;
*--usp = scp->sc_r11;
*--usp = scp->sc_r10;
*--usp = scp->sc_r9;
*--usp = scp->sc_r8;
sc_reply_port = scp->sc_reply_port;
usp = (uintptr_t *) (scp->sc_ursp - 128);
/* Switch to the user's stack that we have just prepared, and call
__sigreturn2. Clobber "memory" to make sure GCC flushes the stack
setup to actual memory. We align the stack as per the ABI, but pass
the original usp to __sigreturn2 as an argument. */
asm volatile ("movq %1, %%rsp\n"
"andq $-16, %%rsp\n"
"call __sigreturn2" :
: "D" (ss), "S" (usp), "d" (scp)
: "memory");
__builtin_unreachable ();
}
*--usp = scp->sc_rip;
*--usp = scp->sc_rfl;
*--usp = scp->sc_rax;
*--usp = scp->sc_rcx;
*--usp = scp->sc_rdx;
*--usp = scp->sc_rbx;
*--usp = scp->sc_rbp;
*--usp = scp->sc_rsi;
*--usp = scp->sc_rdi;
*--usp = scp->sc_r15;
*--usp = scp->sc_r14;
*--usp = scp->sc_r13;
*--usp = scp->sc_r12;
*--usp = scp->sc_r11;
*--usp = scp->sc_r10;
*--usp = scp->sc_r9;
*--usp = scp->sc_r8;
/* Switch to the user's stack that we have just prepared, and call
__sigreturn2. Clobber "memory" to make sure GCC flushes the stack
setup to actual memory. We align the stack as per the ABI, but pass
the original usp to __sigreturn2 as an argument. */
asm volatile ("movq %1, %%rsp\n"
"andq $-16, %%rsp\n"
"call __sigreturn2" :
: "D" (ss), "S" (usp), "d" (sc_reply_port)
: "memory");
__builtin_unreachable ();
}
weak_alias (__sigreturn, sigreturn)