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author | Laszlo Ersek <lersek@redhat.com> | 2020-01-08 23:24:02 +0100 |
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committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2020-01-14 10:53:42 +0000 |
commit | 4cca7923992a13f6b753782f469ee944da2db796 (patch) | |
tree | 1f2135cc8dd0b6c718a6de9ec38001f3647b5d10 /NetworkPkg | |
parent | a56af23f066e2816c67b7c6e64de7ddefcd70780 (diff) | |
download | edk2-4cca7923992a13f6b753782f469ee944da2db796.tar.gz edk2-4cca7923992a13f6b753782f469ee944da2db796.tar.bz2 edk2-4cca7923992a13f6b753782f469ee944da2db796.zip |
NetworkPkg/HttpDxe: fix 32-bit truncation in HTTPS download
When downloading over TLS, each TLS message ("APP packet") is returned as
a (decrypted) fragment table by EFI_TLS_PROTOCOL.ProcessPacket().
The TlsProcessMessage() function in "NetworkPkg/HttpDxe/HttpsSupport.c"
linearizes the fragment table into a single contiguous data block. The
resultant flat data block contains both TLS headers and data.
The HttpsReceive() function parses the actual application data -- in this
case: decrypted HTTP data -- out of the flattened TLS data block, peeling
off the TLS headers.
The HttpResponseWorker() function in "NetworkPkg/HttpDxe/HttpImpl.c"
propagates this HTTP data outwards, implementing the
EFI_HTTP_PROTOCOL.Response() function.
Now consider the following documentation for EFI_HTTP_PROTOCOL.Response(),
quoted from "MdePkg/Include/Protocol/Http.h":
> It is the responsibility of the caller to allocate a buffer for Body and
> specify the size in BodyLength. If the remote host provides a response
> that contains a content body, up to BodyLength bytes will be copied from
> the receive buffer into Body and BodyLength will be updated with the
> amount of bytes received and copied to Body. This allows the client to
> download a large file in chunks instead of into one contiguous block of
> memory.
Note that, if the caller-allocated buffer is larger than the
server-provided chunk, then the transfer length is limited by the latter.
This is in fact the dominant case when downloading a huge file (for which
UefiBootManagerLib allocated a huge contiguous RAM Disk buffer) in small
TLS messages.
For adjusting BodyLength as described above -- i.e., to the application
data chunk that has been extracted from the TLS message --, the
HttpResponseWorker() function employs the following assignment:
HttpMsg->BodyLength = MIN (Fragment.Len, (UINT32) HttpMsg->BodyLength);
The (UINT32) cast is motivated by the MIN() requirement -- in
"MdePkg/Include/Base.h" -- that both arguments be of the same type.
"Fragment.Len" (NET_FRAGMENT.Len) has type UINT32, and
"HttpMsg->BodyLength" (EFI_HTTP_MESSAGE.BodyLength) has type UINTN.
Therefore a cast is indeed necessary.
Unfortunately, the cast is done in the wrong direction. Consider the
following circumstances:
- "Fragment.Len" happens to be consistently 16KiB, dictated by the HTTPS
Server's TLS stack,
- the size of the file to download is 4GiB + N*16KiB, where N is a
positive integer.
As the download progresses, each received 16KiB application data chunk
brings the *next* input value of BodyLength closer down to 4GiB. The cast
in MIN() always masks off the high-order bits from the input value of
BodyLength, but this is no problem because the low-order bits are nonzero,
therefore the MIN() always permits progress.
However, once BodyLength reaches 4GiB exactly on input, the MIN()
invocation produces a zero value. HttpResponseWorker() adjusts the output
value of BodyLength to zero, and then passes it to HttpParseMessageBody().
HttpParseMessageBody() (in "NetworkPkg/Library/DxeHttpLib/DxeHttpLib.c")
rejects the zero BodyLength with EFI_INVALID_PARAMETER, which is fully
propagated outwards, and aborts the HTTPS download. HttpBootDxe writes the
message "Error: Unexpected network error" to the UEFI console.
For example, a file with size (4GiB + 197MiB) terminates after downloading
just 197MiB.
Invert the direction of the cast: widen "Fragment.Len" to UINTN.
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Reviewed-by: Siyuan Fu <siyuan.fu@intel.com>
Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Diffstat (limited to 'NetworkPkg')
-rw-r--r-- | NetworkPkg/HttpDxe/HttpImpl.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/NetworkPkg/HttpDxe/HttpImpl.c b/NetworkPkg/HttpDxe/HttpImpl.c index 6b877314bd..1acbb60d10 100644 --- a/NetworkPkg/HttpDxe/HttpImpl.c +++ b/NetworkPkg/HttpDxe/HttpImpl.c @@ -1348,7 +1348,7 @@ HttpResponseWorker ( //
// Process the received the body packet.
//
- HttpMsg->BodyLength = MIN (Fragment.Len, (UINT32) HttpMsg->BodyLength);
+ HttpMsg->BodyLength = MIN ((UINTN) Fragment.Len, HttpMsg->BodyLength);
CopyMem (HttpMsg->Body, Fragment.Bulk, HttpMsg->BodyLength);
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