compat breakage in preadv() and pwritev() (c44ed965) · Commits · 戴 / test

Fix for a dumb preadv()/pwritev() compat bug - unlike the native variants, the compat_... ones forget to check FMODE_P{READ,WRITE}, so e.g. on pipe the native preadv() will fail with -ESPIPE and compat one will act as readv() and succeed. Not critical, but it's a clear bug with trivial fix, so IMO it's OK for -final. Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/compat.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -1228,6 +1228,8 @@ compat_sys_preadv(unsigned long fd, const struct compat_iovec __user *vec,
		file = fget_light(fd, &fput_needed);
		if (!file)
		return -EBADF;
		ret = -ESPIPE;
		if (file->f_mode & FMODE_PREAD)
		ret = compat_readv(file, vec, vlen, &pos);
		fput_light(file, fput_needed);
		return ret;
		@@ -1285,6 +1287,8 @@ compat_sys_pwritev(unsigned long fd, const struct compat_iovec __user *vec,
		file = fget_light(fd, &fput_needed);
		if (!file)
		return -EBADF;
		ret = -ESPIPE;
		if (file->f_mode & FMODE_PWRITE)
		ret = compat_writev(file, vec, vlen, &pos);
		fput_light(file, fput_needed);
		return ret;

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