The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 89f686a0fb6e473a876a9a60a13aec67a62b9a7e # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025082155-mocker-overripe-4212@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 89f686a0fb6e473a876a9a60a13aec67a62b9a7e Mon Sep 17 00:00:00 2001 From: John David Anglin dave.anglin@bell.net Date: Fri, 25 Jul 2025 13:51:32 -0400 Subject: [PATCH] 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+
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) \