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linux-user: rt_sigprocmask, check read perms first

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Linux kernel does it this way (checks read permission before validating `how`)
and the latest version of ABSL's `AddressIsReadable()` depends on this
behavior.

c.f.  9539ba4308/kernel/signal.c (L3147)
Reviewed-by: Patrick Venture <venture@google.com>
Signed-off-by: Shu-Chun Weng <scw@google.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Patrick Venture <venture@google.com>
Message-Id: <20220126212559.1936290-2-venture@google.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Shu-Chun Weng 2022-01-26 13:25:58 -08:00 committed by Laurent Vivier
parent 33f53ac52a
commit d3ced2a59a
1 changed files with 7 additions and 5 deletions
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12
linux-user/syscall.c
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@ -9478,6 +9478,13 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
} }
if (arg2) { if (arg2) {
p = lock_user(VERIFY_READ, arg2, sizeof(target_sigset_t), 1);
if (!p) {
return -TARGET_EFAULT;
}
target_to_host_sigset(&set, p);
unlock_user(p, arg2, 0);
set_ptr = &set;
switch(how) { switch(how) {
case TARGET_SIG_BLOCK: case TARGET_SIG_BLOCK:
how = SIG_BLOCK; how = SIG_BLOCK;
@ -9491,11 +9498,6 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
default: default:
return -TARGET_EINVAL; return -TARGET_EINVAL;
} }
if (!(p = lock_user(VERIFY_READ, arg2, sizeof(target_sigset_t), 1)))
return -TARGET_EFAULT;
target_to_host_sigset(&set, p);
unlock_user(p, arg2, 0);
set_ptr = &set;
} else { } else {
how = 0; how = 0;
set_ptr = NULL; set_ptr = NULL;