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| 1 | +Source: https://gitlab.gnome.org/GNOME/libxslt/-/commit/c7c7f1f78dd202a053996fcefe57eb994aec8ef2 |
| 2 | +Issue: https://gitlab.gnome.org/GNOME/libxslt/-/issues/128 |
| 3 | +From c7c7f1f78dd202a053996fcefe57eb994aec8ef2 Mon Sep 17 00:00:00 2001 |
| 4 | +From: Nick Wellnhofer < [email protected]> |
| 5 | +Date: Tue, 17 Dec 2024 15:56:21 +0100 |
| 6 | +Subject: [PATCH] [CVE-2025-24855] Fix use-after-free of XPath context node |
| 7 | + |
| 8 | +There are several places where the XPath context node isn't restored |
| 9 | +after modifying it, leading to use-after-free errors with nested XPath |
| 10 | +evaluations and dynamically allocated context nodes. |
| 11 | + |
| 12 | +Restore XPath context node in |
| 13 | + |
| 14 | +- xsltNumberFormatGetValue |
| 15 | +- xsltEvalXPathPredicate |
| 16 | +- xsltEvalXPathStringNs |
| 17 | +- xsltComputeSortResultInternal |
| 18 | + |
| 19 | +In some places, the transformation context node was saved and restored |
| 20 | +which shouldn't be necessary. |
| 21 | + |
| 22 | +Thanks to Ivan Fratric for the report! |
| 23 | + |
| 24 | +Fixes #128. |
| 25 | +--- |
| 26 | + libxslt/numbers.c | 5 +++++ |
| 27 | + libxslt/templates.c | 9 ++++++--- |
| 28 | + libxslt/xsltutils.c | 4 ++-- |
| 29 | + 3 files changed, 13 insertions(+), 5 deletions(-) |
| 30 | + |
| 31 | +diff --git a/libxslt/numbers.c b/libxslt/numbers.c |
| 32 | +index 92023f8..58c61b9 100644 |
| 33 | +--- a/libxslt/numbers.c |
| 34 | ++++ b/libxslt/numbers.c |
| 35 | +@@ -708,9 +708,12 @@ xsltNumberFormatGetValue(xmlXPathContextPtr context, |
| 36 | + int amount = 0; |
| 37 | + xmlBufferPtr pattern; |
| 38 | + xmlXPathObjectPtr obj; |
| 39 | ++ xmlNodePtr oldNode; |
| 40 | + |
| 41 | + pattern = xmlBufferCreate(); |
| 42 | + if (pattern != NULL) { |
| 43 | ++ oldNode = context->node; |
| 44 | ++ |
| 45 | + xmlBufferCCat(pattern, "number("); |
| 46 | + xmlBufferCat(pattern, value); |
| 47 | + xmlBufferCCat(pattern, ")"); |
| 48 | +@@ -723,6 +726,8 @@ xsltNumberFormatGetValue(xmlXPathContextPtr context, |
| 49 | + xmlXPathFreeObject(obj); |
| 50 | + } |
| 51 | + xmlBufferFree(pattern); |
| 52 | ++ |
| 53 | ++ context->node = oldNode; |
| 54 | + } |
| 55 | + return amount; |
| 56 | + } |
| 57 | +diff --git a/libxslt/templates.c b/libxslt/templates.c |
| 58 | +index 48b73a5..a1a6cc8 100644 |
| 59 | +--- a/libxslt/templates.c |
| 60 | ++++ b/libxslt/templates.c |
| 61 | +@@ -61,6 +61,7 @@ xsltEvalXPathPredicate(xsltTransformContextPtr ctxt, xmlXPathCompExprPtr comp, |
| 62 | + int oldNsNr; |
| 63 | + xmlNsPtr *oldNamespaces; |
| 64 | + xmlNodePtr oldInst; |
| 65 | ++ xmlNodePtr oldNode; |
| 66 | + int oldProximityPosition, oldContextSize; |
| 67 | + |
| 68 | + if ((ctxt == NULL) || (ctxt->inst == NULL)) { |
| 69 | +@@ -69,6 +70,7 @@ xsltEvalXPathPredicate(xsltTransformContextPtr ctxt, xmlXPathCompExprPtr comp, |
| 70 | + return(0); |
| 71 | + } |
| 72 | + |
| 73 | ++ oldNode = ctxt->xpathCtxt->node; |
| 74 | + oldContextSize = ctxt->xpathCtxt->contextSize; |
| 75 | + oldProximityPosition = ctxt->xpathCtxt->proximityPosition; |
| 76 | + oldNsNr = ctxt->xpathCtxt->nsNr; |
| 77 | +@@ -96,8 +98,9 @@ xsltEvalXPathPredicate(xsltTransformContextPtr ctxt, xmlXPathCompExprPtr comp, |
| 78 | + ctxt->state = XSLT_STATE_STOPPED; |
| 79 | + ret = 0; |
| 80 | + } |
| 81 | +- ctxt->xpathCtxt->nsNr = oldNsNr; |
| 82 | + |
| 83 | ++ ctxt->xpathCtxt->node = oldNode; |
| 84 | ++ ctxt->xpathCtxt->nsNr = oldNsNr; |
| 85 | + ctxt->xpathCtxt->namespaces = oldNamespaces; |
| 86 | + ctxt->inst = oldInst; |
| 87 | + ctxt->xpathCtxt->contextSize = oldContextSize; |
| 88 | +@@ -137,7 +140,7 @@ xsltEvalXPathStringNs(xsltTransformContextPtr ctxt, xmlXPathCompExprPtr comp, |
| 89 | + } |
| 90 | + |
| 91 | + oldInst = ctxt->inst; |
| 92 | +- oldNode = ctxt->node; |
| 93 | ++ oldNode = ctxt->xpathCtxt->node; |
| 94 | + oldPos = ctxt->xpathCtxt->proximityPosition; |
| 95 | + oldSize = ctxt->xpathCtxt->contextSize; |
| 96 | + oldNsNr = ctxt->xpathCtxt->nsNr; |
| 97 | +@@ -167,7 +170,7 @@ xsltEvalXPathStringNs(xsltTransformContextPtr ctxt, xmlXPathCompExprPtr comp, |
| 98 | + "xsltEvalXPathString: returns %s\n", ret)); |
| 99 | + #endif |
| 100 | + ctxt->inst = oldInst; |
| 101 | +- ctxt->node = oldNode; |
| 102 | ++ ctxt->xpathCtxt->node = oldNode; |
| 103 | + ctxt->xpathCtxt->contextSize = oldSize; |
| 104 | + ctxt->xpathCtxt->proximityPosition = oldPos; |
| 105 | + ctxt->xpathCtxt->nsNr = oldNsNr; |
| 106 | +diff --git a/libxslt/xsltutils.c b/libxslt/xsltutils.c |
| 107 | +index 94097b9..cfe55ce 100644 |
| 108 | +--- a/libxslt/xsltutils.c |
| 109 | ++++ b/libxslt/xsltutils.c |
| 110 | +@@ -1002,8 +1002,8 @@ xsltComputeSortResult(xsltTransformContextPtr ctxt, xmlNodePtr sort) { |
| 111 | + return(NULL); |
| 112 | + } |
| 113 | + |
| 114 | +- oldNode = ctxt->node; |
| 115 | + oldInst = ctxt->inst; |
| 116 | ++ oldNode = ctxt->xpathCtxt->node; |
| 117 | + oldPos = ctxt->xpathCtxt->proximityPosition; |
| 118 | + oldSize = ctxt->xpathCtxt->contextSize; |
| 119 | + oldNsNr = ctxt->xpathCtxt->nsNr; |
| 120 | +@@ -1065,8 +1065,8 @@ xsltComputeSortResult(xsltTransformContextPtr ctxt, xmlNodePtr sort) { |
| 121 | + results[i] = NULL; |
| 122 | + } |
| 123 | + } |
| 124 | +- ctxt->node = oldNode; |
| 125 | + ctxt->inst = oldInst; |
| 126 | ++ ctxt->xpathCtxt->node = oldNode; |
| 127 | + ctxt->xpathCtxt->contextSize = oldSize; |
| 128 | + ctxt->xpathCtxt->proximityPosition = oldPos; |
| 129 | + ctxt->xpathCtxt->nsNr = oldNsNr; |
| 130 | +-- |
| 131 | +2.33.8 |
| 132 | + |
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