Patch "net: ipa: avoid field overflow" has been added to the 5.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: ipa: avoid field overflow

to the 5.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-ipa-avoid-field-overflow.patch
and it can be found in the queue-5.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit cff89b190444a12b0af2c7046a9c8eeac1d7560a
Author: Alex Elder <elder@xxxxxxxxxx>
Date:   Fri Feb 5 16:11:00 2021 -0600

    net: ipa: avoid field overflow
    
    [ Upstream commit cd1150098f2cc7bd05740c105488c293f6761f5a ]
    
    It's possible that the length passed to ipa_header_size_encoded()
    is larger than what can be represented by the HDR_LEN field alone
    (starting with IPA v4.5).  If we attempted that, u32_encode_bits()
    would trigger a build-time error.
    
    Avoid this problem by masking off high-order bits of the value
    encoded as the lower portion of the header length.
    
    The same sort of problem exists in ipa_metadata_offset_encoded(),
    so implement the same fix there.
    
    Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ipa/ipa_reg.h b/drivers/net/ipa/ipa_reg.h
index e6b0827a244e..732e691e9aa6 100644
--- a/drivers/net/ipa/ipa_reg.h
+++ b/drivers/net/ipa/ipa_reg.h
@@ -408,15 +408,18 @@ enum ipa_cs_offload_en {
 static inline u32 ipa_header_size_encoded(enum ipa_version version,
 					  u32 header_size)
 {
+	u32 size = header_size & field_mask(HDR_LEN_FMASK);
 	u32 val;
 
-	val = u32_encode_bits(header_size, HDR_LEN_FMASK);
-	if (version < IPA_VERSION_4_5)
+	val = u32_encode_bits(size, HDR_LEN_FMASK);
+	if (version < IPA_VERSION_4_5) {
+		/* ipa_assert(header_size == size); */
 		return val;
+	}
 
 	/* IPA v4.5 adds a few more most-significant bits */
-	header_size >>= hweight32(HDR_LEN_FMASK);
-	val |= u32_encode_bits(header_size, HDR_LEN_MSB_FMASK);
+	size = header_size >> hweight32(HDR_LEN_FMASK);
+	val |= u32_encode_bits(size, HDR_LEN_MSB_FMASK);
 
 	return val;
 }
@@ -425,15 +428,18 @@ static inline u32 ipa_header_size_encoded(enum ipa_version version,
 static inline u32 ipa_metadata_offset_encoded(enum ipa_version version,
 					      u32 offset)
 {
+	u32 off = offset & field_mask(HDR_OFST_METADATA_FMASK);
 	u32 val;
 
-	val = u32_encode_bits(offset, HDR_OFST_METADATA_FMASK);
-	if (version < IPA_VERSION_4_5)
+	val = u32_encode_bits(off, HDR_OFST_METADATA_FMASK);
+	if (version < IPA_VERSION_4_5) {
+		/* ipa_assert(offset == off); */
 		return val;
+	}
 
 	/* IPA v4.5 adds a few more most-significant bits */
-	offset >>= hweight32(HDR_OFST_METADATA_FMASK);
-	val |= u32_encode_bits(offset, HDR_OFST_METADATA_MSB_FMASK);
+	off = offset >> hweight32(HDR_OFST_METADATA_FMASK);
+	val |= u32_encode_bits(off, HDR_OFST_METADATA_MSB_FMASK);
 
 	return val;
 }