From: Joe Perches <joe@xxxxxxxxxxx> Subject: kernel/sys.c: avoid copying possible padding bytes in copy_to_user Initialization is not guaranteed to zero padding bytes so use an explicit memset instead to avoid leaking any kernel content in any possible padding bytes. Link: http://lkml.kernel.org/r/dfa331c00881d61c8ee51577a082d8bebd61805c.camel@xxxxxxxxxxx Signed-off-by: Joe Perches <joe@xxxxxxxxxxx> Cc: Dan Carpenter <error27@xxxxxxxxx> Cc: Julia Lawall <julia.lawall@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/sys.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/kernel/sys.c~kernel-sysc-avoid-copying-possible-padding-bytes-in-copy_to_user +++ a/kernel/sys.c @@ -1279,11 +1279,13 @@ SYSCALL_DEFINE1(uname, struct old_utsnam SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name) { - struct oldold_utsname tmp = {}; + struct oldold_utsname tmp; if (!name) return -EFAULT; + memset(&tmp, 0, sizeof(tmp)); + down_read(&uts_sem); memcpy(&tmp.sysname, &utsname()->sysname, __OLD_UTS_LEN); memcpy(&tmp.nodename, &utsname()->nodename, __OLD_UTS_LEN); _
