diff options
| author | Alexander Potapenko <glider@google.com> | 2022-10-24 23:21:43 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-10-28 13:37:23 -0700 |
| commit | 59c8a02e24894e75639bcecc3cb1e768a2792220 (patch) | |
| tree | 0a1d7eb39339b0bf5f92d857d252a226435eb7da | |
| parent | 921757bc9b611efc483a548b86769934384e9c79 (diff) | |
| download | linux-59c8a02e24894e75639bcecc3cb1e768a2792220.tar.bz2 | |
x86: asm: make sure __put_user_size() evaluates pointer once
User access macros must ensure their arguments are evaluated only once if
they are used more than once in the macro body. Adding
instrument_put_user() to __put_user_size() resulted in double evaluation
of the `ptr` argument, which led to correctness issues when performing
e.g. unsafe_put_user(..., p++, ...).
To fix those issues, evaluate the `ptr` argument of __put_user_size() at
the beginning of the macro.
Link: https://lkml.kernel.org/r/20221024212144.2852069-4-glider@google.com
Fixes: 888f84a6da4d ("x86: asm: instrument usercopy in get_user() and put_user()")
Signed-off-by: Alexander Potapenko <glider@google.com>
Reported-by: youling257 <youling257@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 8bc614cfe21b..1cc756eafa44 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -254,24 +254,25 @@ extern void __put_user_nocheck_8(void); #define __put_user_size(x, ptr, size, label) \ do { \ __typeof__(*(ptr)) __x = (x); /* eval x once */ \ - __chk_user_ptr(ptr); \ + __typeof__(ptr) __ptr = (ptr); /* eval ptr once */ \ + __chk_user_ptr(__ptr); \ switch (size) { \ case 1: \ - __put_user_goto(__x, ptr, "b", "iq", label); \ + __put_user_goto(__x, __ptr, "b", "iq", label); \ break; \ case 2: \ - __put_user_goto(__x, ptr, "w", "ir", label); \ + __put_user_goto(__x, __ptr, "w", "ir", label); \ break; \ case 4: \ - __put_user_goto(__x, ptr, "l", "ir", label); \ + __put_user_goto(__x, __ptr, "l", "ir", label); \ break; \ case 8: \ - __put_user_goto_u64(__x, ptr, label); \ + __put_user_goto_u64(__x, __ptr, label); \ break; \ default: \ __put_user_bad(); \ } \ - instrument_put_user(__x, ptr, size); \ + instrument_put_user(__x, __ptr, size); \ } while (0) #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT |