From: Pali Rohár pali@kernel.org

mainline inclusion from mainline-v6.10-rc2 commit e2a8910af01653c1c268984855629d71fb81f404 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYRA3 CVE: CVE-2024-49996

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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ReparseDataLength is sum of the InodeType size and DataBuffer size. So to get DataBuffer size it is needed to subtract InodeType's size from ReparseDataLength.

Function cifs_strndup_from_utf16() is currentlly accessing buf->DataBuffer at position after the end of the buffer because it does not subtract InodeType size from the length. Fix this problem and correctly subtract variable len.

Member InodeType is present only when reparse buffer is large enough. Check for ReparseDataLength before accessing InodeType to prevent another invalid memory access.

Major and minor rdev values are present also only when reparse buffer is large enough. Check for reparse buffer size before calling reparse_mkdev().

Fixes: d5ecebc4900d ("smb3: Allow query of symlinks stored as reparse points") Reviewed-by: Paulo Alcantara (Red Hat) pc@manguebit.com Signed-off-by: Pali Rohár pali@kernel.org Signed-off-by: Steve French stfrench@microsoft.com Conflicts: fs/cifs/smb2ops.c fs/smb/client/reparse.c [The cause of the conflict is that the path of the code has changed, and the mainline kernel has changed a lot.] Signed-off-by: Long Li leo.lilong@huawei.com --- fs/cifs/smb2ops.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 580c90a13ca8..d350532f393e 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -2809,6 +2809,12 @@ parse_reparse_posix(struct reparse_posix_data *symlink_buf,

/* See MS-FSCC 2.1.2.6 for the 'NFS' style reparse tags */ len = le16_to_cpu(symlink_buf->ReparseDataLength); + if (len < sizeof(symlink_buf->InodeType)) { + cifs_dbg(VFS, "srv returned malformed nfs buffer\n"); + return -EIO; + } + + len -= sizeof(symlink_buf->InodeType);

if (le64_to_cpu(symlink_buf->InodeType) != NFS_SPECFILE_LNK) { cifs_dbg(VFS, "%lld not a supported symlink type\n",