From: Pali Rohár pali@kernel.org
upstream e2a8910af01653c1c268984855629d71fb81f404 commit.
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 [use variable name symlink_buf, the other buf->InodeType accesses are not used in current version so skip] Signed-off-by: Mahmoud Adam mngyadam@amazon.com --- This fixes CVE-2024-49996. fs/cifs/smb2ops.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 6c30fff8a029e..ee9a1e6550e3c 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -2971,6 +2971,12 @@ 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",
[ Sasha's backport helper bot ]
Hi,
Found matching upstream commit: e2a8910af01653c1c268984855629d71fb81f404
WARNING: Author mismatch between patch and found commit: Backport author: Mahmoud Adam mngyadam@amazon.com Commit author: Pali Rohár pali@kernel.org
Status in newer kernel trees: 6.12.y | Present (exact SHA1) 6.11.y | Present (different SHA1: c173d47b69f0) 6.6.y | Present (different SHA1: c6db81c550ce) 6.1.y | Not found 5.15.y | Not found
Note: The patch differs from the upstream commit: --- --- - 2024-11-22 12:31:36.852804062 -0500 +++ /tmp/tmp.ZKhxfvejkU 2024-11-22 12:31:36.843027135 -0500 @@ -1,3 +1,5 @@ +upstream e2a8910af01653c1c268984855629d71fb81f404 commit. + 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. @@ -18,48 +20,31 @@ 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 +[use variable name symlink_buf, the other buf->InodeType accesses are +not used in current version so skip] +Signed-off-by: Mahmoud Adam mngyadam@amazon.com --- - fs/smb/client/reparse.c | 15 ++++++++++++++- - 1 file changed, 14 insertions(+), 1 deletion(-) +This fixes CVE-2024-49996. + fs/cifs/smb2ops.c | 6 ++++++ + 1 file changed, 6 insertions(+)
-diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c -index 3b48a093cfb1f..8ea7a848aa393 100644 ---- a/fs/smb/client/reparse.c -+++ b/fs/smb/client/reparse.c -@@ -320,9 +320,16 @@ static int parse_reparse_posix(struct reparse_posix_data *buf, - unsigned int len; - u64 type; +diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c +index 6c30fff8a029e..ee9a1e6550e3c 100644 +--- a/fs/cifs/smb2ops.c ++++ b/fs/cifs/smb2ops.c +@@ -2971,6 +2971,12 @@ parse_reparse_posix(struct reparse_posix_data *symlink_buf,
-+ len = le16_to_cpu(buf->ReparseDataLength); -+ if (len < sizeof(buf->InodeType)) { + /* 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(buf->InodeType); -+ - switch ((type = le64_to_cpu(buf->InodeType))) { - case NFS_SPECFILE_LNK: -- len = le16_to_cpu(buf->ReparseDataLength); - data->symlink_target = cifs_strndup_from_utf16(buf->DataBuffer, - len, true, - cifs_sb->local_nls); -@@ -482,12 +489,18 @@ bool cifs_reparse_point_to_fattr(struct cifs_sb_info *cifs_sb, - u32 tag = data->reparse.tag; ++ len -= sizeof(symlink_buf->InodeType);
- if (tag == IO_REPARSE_TAG_NFS && buf) { -+ if (le16_to_cpu(buf->ReparseDataLength) < sizeof(buf->InodeType)) -+ return false; - switch (le64_to_cpu(buf->InodeType)) { - case NFS_SPECFILE_CHR: -+ if (le16_to_cpu(buf->ReparseDataLength) != sizeof(buf->InodeType) + 8) -+ return false; - fattr->cf_mode |= S_IFCHR; - fattr->cf_rdev = reparse_mkdev(buf->DataBuffer); - break; - case NFS_SPECFILE_BLK: -+ if (le16_to_cpu(buf->ReparseDataLength) != sizeof(buf->InodeType) + 8) -+ return false; - fattr->cf_mode |= S_IFBLK; - fattr->cf_rdev = reparse_mkdev(buf->DataBuffer); - break; + if (le64_to_cpu(symlink_buf->InodeType) != NFS_SPECFILE_LNK) { + cifs_dbg(VFS, "%lld not a supported symlink type\n", +-- +2.40.1 + ---
Results of testing on various branches:
| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-5.15.y | Success | Success | | stable/linux-5.10.y | Success | Success | | stable/linux-5.4.y | Success | Success |
Hi,
Thanks for your patch.
FYI: kernel test robot notices the stable kernel rule is not satisfied.
The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#opti...
Rule: The upstream commit ID must be specified with a separate line above the commit text. Subject: [PATCH 5.4/5.10/5.15] cifs: Fix buffer overflow when parsing NFS reparse points Link: https://lore.kernel.org/stable/20241122152943.76044-1-mngyadam%40amazon.com
Please ignore this mail if the patch is not relevant for upstream.
kernel test robot lkp@intel.com writes:
Hi,
Thanks for your patch.
FYI: kernel test robot notices the stable kernel rule is not satisfied.
The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html#opti...
Rule: The upstream commit ID must be specified with a separate line above the commit text. Subject: [PATCH 5.4/5.10/5.15] cifs: Fix buffer overflow when parsing NFS reparse points Link: https://lore.kernel.org/stable/20241122152943.76044-1-mngyadam%40amazon.com
Please ignore this mail if the patch is not relevant for upstream.
The commit id is there but in upstream <sha> commit, wrong format. I've sent a v2.
-MNAdam
linux-stable-mirror@lists.linaro.org
-
kernel test robot -
Mahmoud Adam -
Sasha Levin