diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 6521134057e8f9ef34dbfaf8a0a4e46672a32d3c..856fa409c536408bf6b92039f3c88eeaa8ae53e6 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -117,67 +117,11 @@ __visible bool ex_handler_fprestore(const struct exception_table_entry *fixup,
}
EXPORT_SYMBOL_GPL(ex_handler_fprestore);
-/* Helper to check whether a uaccess fault indicates a kernel bug. */
-static bool bogus_uaccess(struct pt_regs *regs, int trapnr,
- unsigned long fault_addr)
-{
- /* This is the normal case: #PF with a fault address in userspace. */
- if (trapnr == X86_TRAP_PF && fault_addr < TASK_SIZE_MAX)
- return false;
-
- /*
- * This code can be reached for machine checks, but only if the #MC
- * handler has already decided that it looks like a candidate for fixup.
- * This e.g. happens when attempting to access userspace memory which
- * the CPU can't access because of uncorrectable bad memory.
- */
- if (trapnr == X86_TRAP_MC)
- return false;
-
- /*
- * There are two remaining exception types we might encounter here:
- * - #PF for faulting accesses to kernel addresses
- * - #GP for faulting accesses to noncanonical addresses
- * Complain about anything else.
- */
- if (trapnr != X86_TRAP_PF && trapnr != X86_TRAP_GP) {
- WARN(1, "unexpected trap %d in uaccess\n", trapnr);
- return false;
- }
-
- /*
- * This is a faulting memory access in kernel space, on a kernel
- * address, in a usercopy function. This can e.g. be caused by improper
- * use of helpers like __put_user and by improper attempts to access
- * userspace addresses in KERNEL_DS regions.
- * The one (semi-)legitimate exception are probe_kernel_{read,write}(),
- * which can be invoked from places like kgdb, /dev/mem (for reading)
- * and privileged BPF code (for reading).
- * The probe_kernel_*() functions set the kernel_uaccess_faults_ok flag
- * to tell us that faulting on kernel addresses, and even noncanonical
- * addresses, in a userspace accessor does not necessarily imply a
- * kernel bug, root might just be doing weird stuff.
- */
- if (current->kernel_uaccess_faults_ok)
- return false;
-
- /* This is bad. Refuse the fixup so that we go into die(). */
- if (trapnr == X86_TRAP_PF) {
- pr_emerg("BUG: pagefault on kernel address 0x%lx in non-whitelisted uaccess\n",
- fault_addr);
- } else {
- pr_emerg("BUG: GPF in non-whitelisted uaccess (non-canonical address?)\n");
- }
- return true;
-}
-
__visible bool ex_handler_uaccess(const struct exception_table_entry *fixup,
struct pt_regs *regs, int trapnr,
unsigned long error_code,
unsigned long fault_addr)
{
- if (bogus_uaccess(regs, trapnr, fault_addr))
- return false;
regs->ip = ex_fixup_addr(fixup);
return true;
}
@@ -188,8 +132,6 @@ __visible bool ex_handler_ext(const struct exception_table_entry *fixup,
unsigned long error_code,
unsigned long fault_addr)
{
- if (bogus_uaccess(regs, trapnr, fault_addr))
- return false;
/* Special hack for uaccess_err */
current->thread.uaccess_err = 1;
regs->ip = ex_fixup_addr(fixup);
diff --git a/fs/namespace.c b/fs/namespace.c
index a677b59efd74e25f52fd3db3e610c6c5193fb171..678ef175d63ae7f4b81efc595e4dd82b2c4b8741 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2698,7 +2698,6 @@ static long exact_copy_from_user(void *to, const void __user * from,
if (!access_ok(from, n))
return n;
- current->kernel_uaccess_faults_ok++;
while (n) {
if (__get_user(c, f)) {
memset(t, 0, n);
@@ -2708,7 +2707,6 @@ static long exact_copy_from_user(void *to, const void __user * from,
f++;
n--;
}
- current->kernel_uaccess_faults_ok--;
return n;
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index bba3afb4e9bf8a782200246ebe8d019be5c7b700..f9b43c989577fdf50da7147ee28a7b0a8c4e24ad 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -739,12 +739,6 @@ struct task_struct {
unsigned use_memdelay:1;
#endif
- /*
- * May usercopy functions fault on kernel addresses?
- * This is not just a single bit because this can potentially nest.
- */
- unsigned int kernel_uaccess_faults_ok;
-
unsigned long atomic_flags; /* Flags requiring atomic access. */
struct restart_block restart_block;
diff --git a/mm/maccess.c b/mm/maccess.c
index f3416632e5a4137c960434c9a59f92a79e0e0204..ec00be51a24fd6a9639897fafeea3abd45b9d3f4 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -30,10 +30,8 @@ long __probe_kernel_read(void *dst, const void *src, size_t size)
set_fs(KERNEL_DS);
pagefault_disable();
- current->kernel_uaccess_faults_ok++;
ret = __copy_from_user_inatomic(dst,
(__force const void __user *)src, size);
- current->kernel_uaccess_faults_ok--;
pagefault_enable();
set_fs(old_fs);
@@ -60,9 +58,7 @@ long __probe_kernel_write(void *dst, const void *src, size_t size)
set_fs(KERNEL_DS);
pagefault_disable();
- current->kernel_uaccess_faults_ok++;
ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
- current->kernel_uaccess_faults_ok--;
pagefault_enable();
set_fs(old_fs);
@@ -98,13 +94,11 @@ long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
set_fs(KERNEL_DS);
pagefault_disable();
- current->kernel_uaccess_faults_ok++;
do {
ret = __get_user(*dst++, (const char __user __force *)src++);
} while (dst[-1] && ret == 0 && src - unsafe_addr < count);
- current->kernel_uaccess_faults_ok--;
dst[-1] = '\0';
pagefault_enable();
set_fs(old_fs);