diff options
| author | John David Anglin <dave.anglin@bell.net> | 2025-07-25 13:51:32 -0400 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2025-07-25 22:45:24 +0200 |
| commit | 89f686a0fb6e473a876a9a60a13aec67a62b9a7e (patch) | |
| tree | d0aacf428dc247b16ce05b6845fe3e48fa3a1688 | |
| parent | f6334f4ae9a4e962ba74b026e1d965dfdf8cbef8 (diff) | |
parisc: Revise __get_user() to probe user read access
Because of the way read access support is implemented, read access
interruptions are only triggered at privilege levels 2 and 3. The
kernel executes at privilege level 0, so __get_user() never triggers
a read access interruption (code 26). Thus, it is currently possible
for user code to access a read protected address via a system call.
Fix this by probing read access rights at privilege level 3 (PRIV_USER)
and setting __gu_err to -EFAULT (-14) if access isn't allowed.
Note the cmpiclr instruction does a 32-bit compare because COND macro
doesn't work inside asm.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v5.12+
| -rw-r--r-- | arch/parisc/include/asm/uaccess.h | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h index 88d0ae5769dd..6c531d2c847e 100644 --- a/arch/parisc/include/asm/uaccess.h +++ b/arch/parisc/include/asm/uaccess.h @@ -42,9 +42,24 @@ __gu_err; \ }) -#define __get_user(val, ptr) \ -({ \ - __get_user_internal(SR_USER, val, ptr); \ +#define __probe_user_internal(sr, error, ptr) \ +({ \ + __asm__("\tproberi (%%sr%1,%2),%3,%0\n" \ + "\tcmpiclr,= 1,%0,%0\n" \ + "\tldi %4,%0\n" \ + : "=r"(error) \ + : "i"(sr), "r"(ptr), "i"(PRIV_USER), \ + "i"(-EFAULT)); \ +}) + +#define __get_user(val, ptr) \ +({ \ + register long __gu_err; \ + \ + __gu_err = __get_user_internal(SR_USER, val, ptr); \ + if (likely(!__gu_err)) \ + __probe_user_internal(SR_USER, __gu_err, ptr); \ + __gu_err; \ }) #define __get_user_asm(sr, val, ldx, ptr) \ |