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Date: Sat, 25 May 2019 14:43:04 -0700 From: Andrew Morton <akpm@...ux-foundation.org> To: Jann Horn <jannh@...gle.com> Cc: Alexander Viro <viro@...iv.linux.org.uk>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>, Nicolas Pitre <nicolas.pitre@...aro.org>, Arnd Bergmann <arnd@...db.de>, Geert Uytterhoeven <geert@...ux-m68k.org>, linux-m68k@...r.kernel.org, Russell King <linux@...linux.org.uk>, linux-arm-kernel@...ts.infradead.org Subject: Re: [PATCH] binfmt_flat: make load_flat_shared_library() work On Fri, 24 May 2019 22:18:17 +0200 Jann Horn <jannh@...gle.com> wrote: > load_flat_shared_library() is broken: It only calls load_flat_file() if > prepare_binprm() returns zero, but prepare_binprm() returns the number of > bytes read - so this only happens if the file is empty. ouch. > Instead, call into load_flat_file() if the number of bytes read is > non-negative. (Even if the number of bytes is zero - in that case, > load_flat_file() will see nullbytes and return a nice -ENOEXEC.) > > In addition, remove the code related to bprm creds and stop using > prepare_binprm() - this code is loading a library, not a main executable, > and it only actually uses the members "buf", "file" and "filename" of the > linux_binprm struct. Instead, call kernel_read() directly. > > Cc: stable@...r.kernel.org > Fixes: 287980e49ffc ("remove lots of IS_ERR_VALUE abuses") > Signed-off-by: Jann Horn <jannh@...gle.com> > --- > I only found the bug by looking at the code, I have not verified its > existence at runtime. > Also, this patch is compile-tested only. > It would be nice if someone who works with nommu Linux could have a > look at this patch. 287980e49ffc was three years ago! Has it really been broken for all that time? If so, it seems a good source of freed disk space...
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