Commit cc4b1242 authored Dec 06, 2018 by Aurelien Jarno Committed by Al Viro Feb 16, 2019

vfs: fix preadv64v2 and pwritev64v2 compat syscalls with offset == -1



The preadv2 and pwritev2 syscalls are supposed to emulate the readv and
writev syscalls when offset == -1. Therefore the compat code should
check for offset before calling do_compat_preadv64 and
do_compat_pwritev64. This is the case for the preadv2 and pwritev2
syscalls, but handling of offset == -1 is missing in their 64-bit
equivalent.

This patch fixes that, calling do_compat_readv and do_compat_writev when
offset == -1. This fixes the following glibc tests on x32:
 - misc/tst-preadvwritev2
 - misc/tst-preadvwritev64v2

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 01e7187b

fs/read_write.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -1238,6 +1238,9 @@ COMPAT_SYSCALL_DEFINE5(preadv64v2, unsigned long, fd,
		const struct compat_iovec __user *,vec,
		unsigned long, vlen, loff_t, pos, rwf_t, flags)
		{
		if (pos == -1)
		return do_compat_readv(fd, vec, vlen, flags);

		return do_compat_preadv64(fd, vec, vlen, pos, flags);
		}
		#endif
		@@ -1344,6 +1347,9 @@ COMPAT_SYSCALL_DEFINE5(pwritev64v2, unsigned long, fd,
		const struct compat_iovec __user *,vec,
		unsigned long, vlen, loff_t, pos, rwf_t, flags)
		{
		if (pos == -1)
		return do_compat_writev(fd, vec, vlen, flags);

		return do_compat_pwritev64(fd, vec, vlen, pos, flags);
		}
		#endif

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