Date: Thu, 19 Jul 2001 11:17:28 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Ruslan Ermilov <ru@FreeBSD.ORG> Cc: security@FreeBSD.ORG Subject: Re: [PATCH] Re: FreeBSD remote root exploit ? Message-ID: <200107191817.f6JIHSJ76262@earth.backplane.com> References: <5.1.0.14.0.20010719001357.03e22638@192.168.0.12> <014d01c11031$bdab5a10$2001a8c0@clitoris> <20010719201407.B61061@sunbay.com> <003701c11077$b3125400$0d00a8c0@alexus> <3B5718A0.2B650C9C@oksala.org> <200107191752.f6JHqer75736@earth.backplane.com> <20010719205948.D67829@sunbay.com>
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:> the ENCRYPT code) where this is true. This patch will fix the existing :> options-based hole, but doesn't close it. :> :Doesn't this handle this? : :int :output_data(const char *format, ...) :{ : va_list args; : size_t remaining, ret; : va_start(args, format); : remaining = BUFSIZ - (nfrontp - netobuf); : /* try a netflush() if the room is too low */ : if (strlen(format) > remaining || BUFSIZ / 4 > remaining) { : ^^^^^^^^^^^^^^^^^^^^^^^^^^ Nope. What if the format is "%d" and the number is "123"? Or that format is "%s" and the argument is "abcdefghijklmnopqrstuvwxyz"? Then strlen(format) could be < remaining but the result of the vsnprintf() could still be > remaining. The output_data() calls for the various options are safe, strlen(format) will always be larger then the actual formatted result. But the debugging and crypto calls to output_data() are not safe. -Matt : netflush(); : remaining = BUFSIZ - (nfrontp - netobuf); : } : ret = vsnprintf(nfrontp, remaining, format, args); To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message
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