48 lines
1.9 KiB
Diff
48 lines
1.9 KiB
Diff
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From 3e388ac4eba63b466bf6b14b2088ea44c8a2bfe4 Mon Sep 17 00:00:00 2001
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From: Krzysztof Kozlowski <krzk@kernel.org>
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Date: Thu, 12 Jul 2018 18:13:16 +0200
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Subject: [PATCH] Fix possible buffer overflow with strncpy and
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-Wstringop-truncation warning
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If valid cipher name (to which netlink socket was bound) is longer than
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CRYPTO_MAX_ALG_NAME defined in lib/cryptouser.h, then the strncpy() will
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try to copy length of this cipher name into smaller buffer.
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In libkcapi the CRYPTO_MAX_ALG_NAME (thus the size of the buffer) is
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defined as 64 but since commit f437a3f477cc ("crypto: api - Extend
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algorithm name limit to 128 bytes") in Linux kernel (v4.12), the kernel
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defines it as 128.
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It is error-prone to use source buffer length as limit of dst buffer.
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Instead choose sizeof(dst buffer).
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This also fixes the warning with GCC v8.1.0:
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lib/kcapi-kernel-if.c: In function '__kcapi_common_getinfo.isra.2':
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lib/kcapi-kernel-if.c:632:3: error: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
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strncpy(req.cru.cru_name, ciphername, strlen(ciphername));
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^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
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Signed-off-by: Stephan Mueller <smueller@chronox.de>
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---
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lib/kcapi-kernel-if.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/lib/kcapi-kernel-if.c b/lib/kcapi-kernel-if.c
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index 2481f8a..807cbfe 100644
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--- a/lib/kcapi-kernel-if.c
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+++ b/lib/kcapi-kernel-if.c
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@@ -627,9 +627,9 @@ static int __kcapi_common_getinfo(struct kcapi_handle *handle,
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if (drivername)
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strncpy(req.cru.cru_driver_name, ciphername,
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- strlen(ciphername));
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+ sizeof(req.cru.cru_driver_name) - 1);
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else
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- strncpy(req.cru.cru_name, ciphername, strlen(ciphername));
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+ strncpy(req.cru.cru_name, ciphername, sizeof(req.cru.cru_name) - 1);
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/* talk to netlink socket */
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sd = socket(AF_NETLINK, SOCK_RAW, NETLINK_CRYPTO);
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