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fs/binfmt_flat.c: make load_flat_shared_library() work
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.
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.
Link: http://lkml.kernel.org/r/20190524201817.16509-1-jannh@google.com
Fixes: 287980e49f
("remove lots of IS_ERR_VALUE abuses")
Signed-off-by: Jann Horn <jannh@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
29b190fa77
commit
867bfa4a5f
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@ -856,9 +856,14 @@ static int load_flat_file(struct linux_binprm *bprm,
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static int load_flat_shared_library(int id, struct lib_info *libs)
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{
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/*
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* This is a fake bprm struct; only the members "buf", "file" and
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* "filename" are actually used.
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*/
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struct linux_binprm bprm;
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int res;
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char buf[16];
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loff_t pos = 0;
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memset(&bprm, 0, sizeof(bprm));
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@ -872,25 +877,11 @@ static int load_flat_shared_library(int id, struct lib_info *libs)
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if (IS_ERR(bprm.file))
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return res;
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bprm.cred = prepare_exec_creds();
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res = -ENOMEM;
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if (!bprm.cred)
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goto out;
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res = kernel_read(bprm.file, bprm.buf, BINPRM_BUF_SIZE, &pos);
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/* We don't really care about recalculating credentials at this point
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* as we're past the point of no return and are dealing with shared
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* libraries.
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*/
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bprm.called_set_creds = 1;
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res = prepare_binprm(&bprm);
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if (!res)
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if (res >= 0)
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res = load_flat_file(&bprm, libs, id, NULL);
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abort_creds(bprm.cred);
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out:
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allow_write_access(bprm.file);
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fput(bprm.file);
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