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tracing: Have the user copy of synthetic event address use correct context 

commit 4f7969bcd6d33042d62e249b41b5578161e4c868 upstream.

A synthetic event is created by the synthetic event interface that can
read both user or kernel address memory. In reality, it reads any
arbitrary memory location from within the kernel. If the address space is
in USER (where CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE is set) then
it uses strncpy_from_user_nofault() to copy strings otherwise it uses
strncpy_from_kernel_nofault().

But since both functions use the same variable there's no annotation to
what that variable is (ie. __user). This makes sparse complain.

Quiet sparse by typecasting the strncpy_from_user_nofault() variable to
a __user pointer.

Link: https://lore.kernel.org/linux-trace-kernel/20231031151033.73c42e23@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 0934ae9977 ("tracing: Fix reading strings from synthetic events");
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311010013.fm8WTxa5-lkp@intel.com/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Steven Rostedt (Google) 2023-10-31 15:10:33 -04:00 committed by Greg Kroah-Hartman
parent 185f3617ad
commit f7ab9dee22
1 changed files with 1 additions and 1 deletions
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kernel/trace/trace_events_synth.c
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@ -473,7 +473,7 @@ static unsigned int trace_string(struct synth_trace_event *entry,
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if ((unsigned long)str_val < TASK_SIZE)
ret = strncpy_from_user_nofault(str_field, str_val, STR_VAR_LEN_MAX);
ret = strncpy_from_user_nofault(str_field, (const void __user *)str_val, STR_VAR_LEN_MAX);
else
#endif
ret = strncpy_from_kernel_nofault(str_field, str_val, STR_VAR_LEN_MAX);