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tty: vt/keyboard: Split apart vt_do_diacrit()

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After commit bfb24564b5 ("tty: vt/keyboard: use __free()"), builds
using asm goto for put_user() and get_user() with a version of clang
older than 17 error with:

  drivers/tty/vt/keyboard.c:1709:7: error: cannot jump from this asm goto statement to one of its possible targets
                  if (put_user(asize, &a->kb_cnt))
                      ^
  ...
  arch/arm64/include/asm/uaccess.h:298:2: note: expanded from macro '__put_mem_asm'
          asm goto(                                                       \
          ^
  drivers/tty/vt/keyboard.c:1687:7: note: possible target of asm goto statement
                  if (put_user(asize, &a->kb_cnt))
                      ^
  ...
  arch/arm64/include/asm/uaccess.h:342:2: note: expanded from macro '__raw_put_user'
          __rpu_failed:                                                   \
          ^
  drivers/tty/vt/keyboard.c:1697:23: note: jump exits scope of variable with __attribute__((cleanup))
                  void __free(kfree) *buf = kmalloc_array(MAX_DIACR, sizeof(struct kbdiacruc),
                                      ^
  drivers/tty/vt/keyboard.c:1671:33: note: jump bypasses initialization of variable with __attribute__((cleanup))
                  struct kbdiacr __free(kfree) *dia = kmalloc_array(MAX_DIACR, sizeof(struct kbdiacr),
                                                ^

Prior to a fix to clang's scope checker in clang 17 [1], all labels in a
function were validated as potential targets of all asm gotos in a
function, regardless of whether they actually were a target of an asm
goto call, resulting in false positive errors about skipping over
variables marked with the cleanup attribute.

To workaround this error, split up the bodies of the case statements in
vt_do_diacrit() into their own functions so that the scope checker does
not trip up on the multiple instances of __free().

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509091702.Oc7eCRDw-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202511241835.EA8lShgH-lkp@intel.com/
Link: f023f5cdb2 [1]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20251125-tty-vt-keyboard-wa-clang-scope-check-error-v1-1-f5a5ea55c578@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nathan Chancellor 2025-11-25 15:54:37 -07:00 • committed by Greg Kroah-Hartman
commit 0a76a17238
1 changed files with 115 additions and 106 deletions
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