Date: Mon, 9 May 2016 16:06:42 +0200 From: Marko Turk <markoml@markoturk.info> To: twilight <pipfstarrd@openmailbox.org> Cc: freebsd-questions@freebsd.org Subject: Re: Bug with pointer corruption when assigning smth to dereferenced pointer (part of a structure) Message-ID: <20160509140642.GA2689@vps.markoturk.info> In-Reply-To: <4b9ef7c8-20e2-a004-9f3a-0ee564179513@openmailbox.org> References: <4b9ef7c8-20e2-a004-9f3a-0ee564179513@openmailbox.org>
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[-- Attachment #1 --] On Mon, May 09, 2016 at 01:39:32PM +0000, twilight wrote: > Hello! > > When I were working on my FreeBSD-powered ThinkPad X200 I encounted a > bug (not sure what causes that) that produced a segfault. After some > investigation I were able to cut down the problem to such a small piece > of code: https://ideone.com/VVtgpG. > > As you can see on ideone, it works absolutely fine. > But in my case I have: > > ############################### > In main we've got > container->first: 0x801006060 > container->last 0x801006060 > container: 0x801006058 > > In main after change we've got > container->first: 0x801006060 > container->last 0x800000005 > container: 0x801006058 > ############################### > > > I've wondered if it's hardware related or compiler related, so at first > I tried to compile with gcc and got the same result. Then, I tried to > compile and run the same on Ubuntu Live USB (with gcc). Everything > worked like a charm. > > Here's the generated asm code: http://pastebin.com/8yRyk5nG. > > Any suggestions where to submit the bug or what extra information to > provide? Hi, you have a bug in your code: Container *container = (Container*) malloc(sizeof(Container*)); This line will not malloc enough space for Container structure. BR, Marko [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJXMJlxAAoJEHg6bF2mqM2ImzgQALmW/oksaUP+/3t+ClmVE9IQ hD70eLn3lrdoymZiuYx1NYqYYT4sSV8Tp5oXpA3Il42nIEsQPiS8UaoPrwAldbml 1LrC2gpACzyNAUZIGBho2f6vFxdX5RbGJ0ZI+glfsIRDvyewQU0j5gIT+VvFpf0j DNop3ab14zFu41KtBt3rF7xciPTeE6MIn8AZkYPL8hBbahlz+6KkMsjBN3H7HbZB vbwU5q9JsPyE3fbaDaY0csT/QmYSSU8UoOb589kamF2CAQLokkhn/mo2yACq6H1l DAf240YOtxD8HK/V4I3aX7+H3dEqvGG7wTf08YoMJqJLZX3f5fsUmK3nyNRx7Ylx EvAF0W8EcUjfTcahhIpTUVwhY4wNP3q6nNZSiEaxvsYfl+cynMW2Y8OwSEQ9cV+z nrqdpKL+duUANfICabo0OWxtY9LGycxJALKJhtKnBhuN9rFnh5eATDH2/rnFqcQJ 9EWMVfcM7s7C5JtK1Y9buppyQKrgCTCH/712FjIUzVutTPWBiHaBwGW1BTTV6tx0 br+7EVKJYQfi6AG0So8y/D7UMjN47jm9GovGMqckTgyEzCOIMoj47yO2Br2O1LUe zymPvGLSqzYnPMeQePuokUWkY+b/E6WTNke+wtLDGeWa+HwKMaYWhOhRIexzMDCI yQ5RVl7ECuzrbm979p52 =04AC -----END PGP SIGNATURE-----help
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