diff options
| author | John David Anglin <dave.anglin@bell.net> | 2025-07-25 13:51:32 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-28 16:31:00 +0200 |
| commit | f410ef9a032caf98117256b22139c31342d7bb06 (patch) | |
| tree | a66f8477c7fecca7bfc59b0061708622fc7c3976 | |
| parent | 1dc6244651eda6fe90898664d2e6a9e415a18c50 (diff) | |
parisc: Revise __get_user() to probe user read access
commit 89f686a0fb6e473a876a9a60a13aec67a62b9a7e upstream.
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+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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) \ |