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iov_iter: Mark copy_compat_iovec_from_user() noinline 

After commit 6376ce56feb6 ("iov_iter: import single vector iovecs as
ITER_UBUF"), GCC does an inter-procedural compiler optimization which
moves the user_access_begin() out of copy_compat_iovec_from_user() and
into its callers:

  lib/iov_iter.o: warning: objtool: .altinstr_replacement+0x0: redundant UACCESS disable
  lib/iov_iter.o: warning: objtool: iovec_from_user.part.0+0xc7: call to copy_compat_iovec_from_user.part.0() with UACCESS enabled
  lib/iov_iter.o: warning: objtool: __import_iovec+0x21d: call to copy_compat_iovec_from_user.part.0() with UACCESS enabled

Enforce the "no UACCESS enable across function boundaries" rule by
disabling cloning for copy_compat_iovec_from_user().

Fixes: 6376ce56feb6 ("iov_iter: import single vector iovecs as ITER_UBUF")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
https://lkml.kernel.org/lkml/20230327120017.6bb826d7@canb.auug.org.au
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Josh Poimboeuf 2023-04-12 10:46:48 -06:00 committed by Jens Axboe
parent 3b2deb0e46
commit 50f9a76ef1
1 changed files with 1 additions and 1 deletions
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2
lib/iov_iter.c
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@ -1702,7 +1702,7 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
}
EXPORT_SYMBOL(dup_iter);
static int copy_compat_iovec_from_user(struct iovec *iov,
static __noclone int copy_compat_iovec_from_user(struct iovec *iov,
const struct iovec __user *uvec, unsigned long nr_segs)
{
const struct compat_iovec __user *uiov =