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From: "Tobin C. Harding" <me@tobin.cc>
To: kernel-hardening@lists.openwall.com
Cc: "Tobin C. Harding" <me@tobin.cc>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
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        Network Development <netdev@vger.kernel.org>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] kallsyms: don't leak address when printing symbol
Date: Thu,  9 Nov 2017 12:50:29 +1100
Message-Id: <1510192229-20038-1-git-send-email-me@tobin.cc>
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Currently if a pointer is printed using %p[ssB] and the symbol is not
found (kallsyms_lookup() fails) then we print the actual address. This
leaks kernel addresses. We should instead print something _safe_.

Print "<no-symbol>" instead of kernel address.

Signed-off-by: Tobin C. Harding <me@tobin.cc>
---
 kernel/kallsyms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 127e7cfafa55..182e7592be9c 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -390,7 +390,7 @@ static int __sprint_symbol(char *buffer, unsigned long address,
 	address += symbol_offset;
 	name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
 	if (!name)
-		return sprintf(buffer, "0x%lx", address - symbol_offset);
+		return sprintf(buffer, "<no-symbol>");
 
 	if (name != buffer)
 		strcpy(buffer, name);
-- 
2.7.4