Remove the insecure 0777 mode for temporary file to prohibit other users to change the executable mapped code.
An attacker could gain access to the mapped file descriptor from the temporary file (before it is unlinked) in a read-only mode but it should not be accessible in write mode to avoid arbitrary code execution. To not change the hostfs behavior, the temporary file creation permission now depends on the current umask(2) and the implementation of mkstemp(3). Signed-off-by: Mickaël Salaün <m...@digikod.net> Cc: Jeff Dike <jd...@addtoit.com> Cc: Richard Weinberger <rich...@nod.at> Acked-by: Tristan Schmelcher <tschmelc...@google.com> --- arch/um/os-Linux/mem.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index 897e9ad0c108..840d573f7e38 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -142,12 +142,6 @@ static int __init create_tmp_file(unsigned long long len) if (fd < 0) exit(1); - err = fchmod(fd, 0777); - if (err < 0) { - perror("fchmod"); - exit(1); - } - /* * Seek to len - 1 because writing a character there will * increase the file size by one byte, to the desired length. -- 2.6.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/