4.14-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit cc4b1242d7e3b42eed73881fc749944146493e4f ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/read_write.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/read_write.c b/fs/read_write.c index 57a00ef895b2..1c3eada2fe25 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1235,6 +1235,9 @@ 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 @@ -1341,6 +1344,9 @@ 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