From: Tristan Madani Date: Tue, 5 May 2026 11:12:58 +0000 (+0000) Subject: hfs/hfsplus: fix u32 overflow in check_and_correct_requested_length X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=966cb76fb2857a4242cab6ea2ea17acf818a3da7;p=thirdparty%2Fkernel%2Flinux.git hfs/hfsplus: fix u32 overflow in check_and_correct_requested_length check_and_correct_requested_length() compares (off + len) against node_size using u32 arithmetic. When the caller passes a large len value (e.g. from an underflowed subtraction in hfs_brec_remove()), off + len can wrap past 2^32 and produce a small result, causing the bounds check to pass when it should fail. For example, with off=14 and len=0xFFFFFFF2 (underflowed from data_off - keyoffset - size in hfs_brec_remove), off + len wraps to 6, which is less than a typical node_size of 512, so the check passes and the subsequent memmove reads ~4GB past the node buffer. Fix this by widening the addition to u64 before comparing against node_size. This prevents the u32 wrap while keeping the logic straightforward. Reported-by: syzbot+6df204b70bf3261691c5@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=6df204b70bf3261691c5 Tested-by: syzbot+6df204b70bf3261691c5@syzkaller.appspotmail.com Reported-by: syzbot+e76bf3d19b85350571ac@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e76bf3d19b85350571ac Tested-by: syzbot+e76bf3d19b85350571ac@syzkaller.appspotmail.com Fixes: a431930c9bac ("hfs: fix slab-out-of-bounds in hfs_bnode_read()") Cc: stable@vger.kernel.org Signed-off-by: Tristan Madani Reviewed-by: Viacheslav Dubeyko Signed-off-by: Viacheslav Dubeyko Link: https://lore.kernel.org/r/20260505111300.3592757-2-tristmd@gmail.com Signed-off-by: Viacheslav Dubeyko --- diff --git a/fs/hfs/bnode.c b/fs/hfs/bnode.c index b0165de7640db..3a8a3878d7b08 100644 --- a/fs/hfs/bnode.c +++ b/fs/hfs/bnode.c @@ -41,7 +41,7 @@ u32 check_and_correct_requested_length(struct hfs_bnode *node, u32 off, u32 len) node_size = node->tree->node_size; - if ((off + len) > node_size) { + if ((u64)off + len > node_size) { u32 new_len = node_size - off; pr_err("requested length has been corrected: " diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h index 3545b8dbf11c5..0e4268de9e60e 100644 --- a/fs/hfsplus/hfsplus_fs.h +++ b/fs/hfsplus/hfsplus_fs.h @@ -600,7 +600,7 @@ u32 check_and_correct_requested_length(struct hfs_bnode *node, u32 off, u32 len) node_size = node->tree->node_size; - if ((off + len) > node_size) { + if ((u64)off + len > node_size) { u32 new_len = node_size - off; pr_err("requested length has been corrected: "