f2fs: avoid utf8_strncasecmp() with unstable name

If the dentry name passed to ->d_compare() fits in dentry::d_iname, then
it may be concurrently modified by a rename.  This can cause undefined
behavior (possibly out-of-bounds memory accesses or crashes) in
utf8_strncasecmp(), since fs/unicode/ isn't written to handle strings
that may be concurrently modified.

Fix this by first copying the filename to a stack buffer if needed.
This way we get a stable snapshot of the filename.

Fixes: 2c2eb7a300cd ("f2fs: Support case-insensitive file name lookups")
Cc: <[email protected]> # v5.4+
Cc: Al Viro <[email protected]>
Cc: Daniel Rosenberg <[email protected]>
Cc: Gabriel Krisman Bertazi <[email protected]>
Signed-off-by: Eric Biggers <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
Signed-off-by: Jaegeuk Kim <[email protected]>

0 files changed, 0 insertions, 0 deletions