5.4-stable patches

added patches:
	arm64-fix-compat-syscall-return-truncation.patch

diff --git a/queue-5.4/arm64-fix-compat-syscall-return-truncation.patch b/queue-5.4/arm64-fix-compat-syscall-return-truncation.patch
new file mode 100644 (file)
index 0000000..b73497d
--- /dev/null
+++ b/queue-5.4/arm64-fix-compat-syscall-return-truncation.patch
@@ -0,0 +1,176 @@
+From e30e8d46cf605d216a799a28c77b8a41c328613a Mon Sep 17 00:00:00 2001
+From: Mark Rutland <mark.rutland@arm.com>
+Date: Mon, 2 Aug 2021 11:42:00 +0100
+Subject: arm64: fix compat syscall return truncation
+
+From: Mark Rutland <mark.rutland@arm.com>
+
+commit e30e8d46cf605d216a799a28c77b8a41c328613a upstream.
+
+Due to inconsistencies in the way we manipulate compat GPRs, we have a
+few issues today:
+
+* For audit and tracing, where error codes are handled as a (native)
+  long, negative error codes are expected to be sign-extended to the
+  native 64-bits, or they may fail to be matched correctly. Thus a
+  syscall which fails with an error may erroneously be identified as
+  failing.
+
+* For ptrace, *all* compat return values should be sign-extended for
+  consistency with 32-bit arm, but we currently only do this for
+  negative return codes.
+
+* As we may transiently set the upper 32 bits of some compat GPRs while
+  in the kernel, these can be sampled by perf, which is somewhat
+  confusing. This means that where a syscall returns a pointer above 2G,
+  this will be sign-extended, but will not be mistaken for an error as
+  error codes are constrained to the inclusive range [-4096, -1] where
+  no user pointer can exist.
+
+To fix all of these, we must consistently use helpers to get/set the
+compat GPRs, ensuring that we never write the upper 32 bits of the
+return code, and always sign-extend when reading the return code.  This
+patch does so, with the following changes:
+
+* We re-organise syscall_get_return_value() to always sign-extend for
+  compat tasks, and reimplement syscall_get_error() atop. We update
+  syscall_trace_exit() to use syscall_get_return_value().
+
+* We consistently use syscall_set_return_value() to set the return
+  value, ensureing the upper 32 bits are never set unexpectedly.
+
+* As the core audit code currently uses regs_return_value() rather than
+  syscall_get_return_value(), we special-case this for
+  compat_user_mode(regs) such that this will do the right thing. Going
+  forward, we should try to move the core audit code over to
+  syscall_get_return_value().
+
+Cc: <stable@vger.kernel.org>
+Reported-by: He Zhe <zhe.he@windriver.com>
+Reported-by: weiyuchen <weiyuchen3@huawei.com>
+Cc: Catalin Marinas <catalin.marinas@arm.com>
+Cc: Will Deacon <will@kernel.org>
+Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
+Link: https://lore.kernel.org/r/20210802104200.21390-1-mark.rutland@arm.com
+Signed-off-by: Will Deacon <will@kernel.org>
+[Mark: trivial conflict resolution for v5.4.y]
+Signed-off-by: Mark Rutland <mark.rutland@arm.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/arm64/include/asm/ptrace.h  |   12 +++++++++++-
+ arch/arm64/include/asm/syscall.h |   19 ++++++++++---------
+ arch/arm64/kernel/ptrace.c       |    2 +-
+ arch/arm64/kernel/signal.c       |    3 ++-
+ arch/arm64/kernel/syscall.c      |    7 ++-----
+ 5 files changed, 26 insertions(+), 17 deletions(-)
+
+--- a/arch/arm64/include/asm/ptrace.h
++++ b/arch/arm64/include/asm/ptrace.h
+@@ -299,7 +299,17 @@ static inline unsigned long kernel_stack
+ 
+ static inline unsigned long regs_return_value(struct pt_regs *regs)
+ {
+-      return regs->regs[0];
++      unsigned long val = regs->regs[0];
++
++      /*
++       * Audit currently uses regs_return_value() instead of
++       * syscall_get_return_value(). Apply the same sign-extension here until
++       * audit is updated to use syscall_get_return_value().
++       */
++      if (compat_user_mode(regs))
++              val = sign_extend64(val, 31);
++
++      return val;
+ }
+ 
+ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
+--- a/arch/arm64/include/asm/syscall.h
++++ b/arch/arm64/include/asm/syscall.h
+@@ -29,22 +29,23 @@ static inline void syscall_rollback(stru
+       regs->regs[0] = regs->orig_x0;
+ }
+ 
+-
+-static inline long syscall_get_error(struct task_struct *task,
+-                                   struct pt_regs *regs)
++static inline long syscall_get_return_value(struct task_struct *task,
++                                          struct pt_regs *regs)
+ {
+-      unsigned long error = regs->regs[0];
++      unsigned long val = regs->regs[0];
+ 
+       if (is_compat_thread(task_thread_info(task)))
+-              error = sign_extend64(error, 31);
++              val = sign_extend64(val, 31);
+ 
+-      return IS_ERR_VALUE(error) ? error : 0;
++      return val;
+ }
+ 
+-static inline long syscall_get_return_value(struct task_struct *task,
+-                                          struct pt_regs *regs)
++static inline long syscall_get_error(struct task_struct *task,
++                                   struct pt_regs *regs)
+ {
+-      return regs->regs[0];
++      unsigned long error = syscall_get_return_value(task, regs);
++
++      return IS_ERR_VALUE(error) ? error : 0;
+ }
+ 
+ static inline void syscall_set_return_value(struct task_struct *task,
+--- a/arch/arm64/kernel/ptrace.c
++++ b/arch/arm64/kernel/ptrace.c
+@@ -1868,7 +1868,7 @@ void syscall_trace_exit(struct pt_regs *
+       audit_syscall_exit(regs);
+ 
+       if (flags & _TIF_SYSCALL_TRACEPOINT)
+-              trace_sys_exit(regs, regs_return_value(regs));
++              trace_sys_exit(regs, syscall_get_return_value(current, regs));
+ 
+       if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
+               tracehook_report_syscall(regs, PTRACE_SYSCALL_EXIT);
+--- a/arch/arm64/kernel/signal.c
++++ b/arch/arm64/kernel/signal.c
+@@ -29,6 +29,7 @@
+ #include <asm/unistd.h>
+ #include <asm/fpsimd.h>
+ #include <asm/ptrace.h>
++#include <asm/syscall.h>
+ #include <asm/signal32.h>
+ #include <asm/traps.h>
+ #include <asm/vdso.h>
+@@ -868,7 +869,7 @@ static void do_signal(struct pt_regs *re
+                    retval == -ERESTART_RESTARTBLOCK ||
+                    (retval == -ERESTARTSYS &&
+                     !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
+-                      regs->regs[0] = -EINTR;
++                      syscall_set_return_value(current, regs, -EINTR, 0);
+                       regs->pc = continue_addr;
+               }
+ 
+--- a/arch/arm64/kernel/syscall.c
++++ b/arch/arm64/kernel/syscall.c
+@@ -50,10 +50,7 @@ static void invoke_syscall(struct pt_reg
+               ret = do_ni_syscall(regs, scno);
+       }
+ 
+-      if (is_compat_task())
+-              ret = lower_32_bits(ret);
+-
+-      regs->regs[0] = ret;
++      syscall_set_return_value(current, regs, 0, ret);
+ }
+ 
+ static inline bool has_syscall_work(unsigned long flags)
+@@ -108,7 +105,7 @@ static void el0_svc_common(struct pt_reg
+       if (has_syscall_work(flags)) {
+               /* set default errno for user-issued syscall(-1) */
+               if (scno == NO_SYSCALL)
+-                      regs->regs[0] = -ENOSYS;
++                      syscall_set_return_value(current, regs, -ENOSYS, 0);
+               scno = syscall_trace_enter(regs);
+               if (scno == NO_SYSCALL)
+                       goto trace_exit;

diff --git a/queue-5.4/series b/queue-5.4/series
index e7098cb6b926277a9fa298e9a835da7f1efeb50b..1104e3087bb3a2a776ad1d51bee93b73aa141c3b 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -82,3 +82,4 @@ reiserfs-check-directory-items-on-read-from-disk.patch
 virt_wifi-fix-error-on-connect.patch
 alpha-send-stop-ipi-to-send-to-online-cpus.patch
 net-qla3xxx-fix-schedule-while-atomic-in-ql_wait_for.patch
+arm64-fix-compat-syscall-return-truncation.patch