From 5f8ddeb879e3b1f0b7486296b3f48666b457296f Mon Sep 17 00:00:00 2001
From: Dricmoy <dricbhattacharjee@gmail.com>
Date: Wed, 16 Sep 2026 17:11:50 -0600
Subject: [PATCH 1/2] GH-51222: [C++] Avoid overflow in binary_slice output
 sizing

---
 cpp/src/arrow/compute/kernels/scalar_string_ascii.cc | 3 ++-
 cpp/src/arrow/compute/kernels/scalar_string_test.cc  | 7 +++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc b/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc
index 8e7b626837fe..6b4d01c66ed9 100644
--- a/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc
+++ b/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc
@@ -2642,7 +2642,8 @@ struct SliceBytesTransform : StringSliceTransformBase {
       // on the resulting slice lengths, so return a worst case estimate.
       return input_bytes;
     }
-    int64_t max_slice_bytes = (opt.stop - opt.start + opt.step - 1) / opt.step;
+    const int64_t stop = std::clamp(opt.stop, -input_bytes, input_bytes);
+    int64_t max_slice_bytes = (stop - opt.start + opt.step - 1) / opt.step;
     return std::min(input_bytes, ninputs * std::max<int64_t>(0, max_slice_bytes));
   }
 
diff --git a/cpp/src/arrow/compute/kernels/scalar_string_test.cc b/cpp/src/arrow/compute/kernels/scalar_string_test.cc
index 74650c1d76c5..66eef0965a7e 100644
--- a/cpp/src/arrow/compute/kernels/scalar_string_test.cc
+++ b/cpp/src/arrow/compute/kernels/scalar_string_test.cc
@@ -2702,6 +2702,13 @@ TYPED_TEST(TestBinaryKernels, SliceBytesBasic) {
 }
 
 TYPED_TEST(TestBinaryKernels, SliceBytesPosPos) {
+  SliceOptions options_default_stop{/*start=*/1};
+  const std::string long_input(300, 'x');
+  this->CheckUnary(
+      "binary_slice", this->template MakeArray<std::string>({"abcdef", long_input}),
+      this->template MakeArray<std::string>({"bcdef", std::string(299, 'x')}),
+      &options_default_stop);
+
   SliceOptions options{2, 4};
   this->CheckUnary(
       "binary_slice",

From 749b54206bb8476b247fe7ea81e22f81c2952f4d Mon Sep 17 00:00:00 2001
From: Dricmoy <dricbhattacharjee@gmail.com>
Date: Wed, 14 Oct 2026 11:11:42 -0600
Subject: [PATCH 2/2] GH-51222: Address binary slice review feedback

---
 .../compute/kernels/scalar_string_ascii.cc     |  2 ++
 .../compute/kernels/scalar_string_test.cc      | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc b/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc
index 6b4d01c66ed9..a743cb171899 100644
--- a/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc
+++ b/cpp/src/arrow/compute/kernels/scalar_string_ascii.cc
@@ -2642,6 +2642,8 @@ struct SliceBytesTransform : StringSliceTransformBase {
       // on the resulting slice lengths, so return a worst case estimate.
       return input_bytes;
     }
+    // SliceOptions uses INT64_MIN/MAX for open-ended bounds. Clamp stop before
+    // arithmetic so equivalent out-of-range indices cannot overflow the size estimate.
     const int64_t stop = std::clamp(opt.stop, -input_bytes, input_bytes);
     int64_t max_slice_bytes = (stop - opt.start + opt.step - 1) / opt.step;
     return std::min(input_bytes, ninputs * std::max<int64_t>(0, max_slice_bytes));
diff --git a/cpp/src/arrow/compute/kernels/scalar_string_test.cc b/cpp/src/arrow/compute/kernels/scalar_string_test.cc
index 66eef0965a7e..733373c25d77 100644
--- a/cpp/src/arrow/compute/kernels/scalar_string_test.cc
+++ b/cpp/src/arrow/compute/kernels/scalar_string_test.cc
@@ -2702,12 +2702,18 @@ TYPED_TEST(TestBinaryKernels, SliceBytesBasic) {
 }
 
 TYPED_TEST(TestBinaryKernels, SliceBytesPosPos) {
+  constexpr auto max = std::numeric_limits<int64_t>::max();
   SliceOptions options_default_stop{/*start=*/1};
   const std::string long_input(300, 'x');
   this->CheckUnary(
       "binary_slice", this->template MakeArray<std::string>({"abcdef", long_input}),
       this->template MakeArray<std::string>({"bcdef", std::string(299, 'x')}),
       &options_default_stop);
+  SliceOptions options_default_stop_step{/*start=*/1, /*stop=*/max, /*step=*/5};
+  this->CheckUnary("binary_slice",
+                   this->template MakeArray<std::string>({"abcdef", long_input}),
+                   this->template MakeArray<std::string>({"b", std::string(60, 'x')}),
+                   &options_default_stop_step);
 
   SliceOptions options{2, 4};
   this->CheckUnary(
@@ -2755,6 +2761,18 @@ TYPED_TEST(TestBinaryKernels, SliceBytesPosNeg) {
 }
 
 TYPED_TEST(TestBinaryKernels, SliceBytesNegNeg) {
+  constexpr auto min = std::numeric_limits<int64_t>::min();
+  const std::string long_input(300, 'x');
+  SliceOptions options_min{/*start=*/-1, /*stop=*/min};
+  this->CheckUnary("binary_slice",
+                   this->template MakeArray<std::string>({"abcdef", long_input}),
+                   this->template MakeArray<std::string>({"", ""}), &options_min);
+  SliceOptions options_min_step_neg{/*start=*/-1, /*stop=*/min, /*step=*/-5};
+  this->CheckUnary("binary_slice",
+                   this->template MakeArray<std::string>({"abcdef", long_input}),
+                   this->template MakeArray<std::string>({"fa", std::string(60, 'x')}),
+                   &options_min_step_neg);
+
   SliceOptions options{-2, -1};
   this->CheckUnary(
       "binary_slice",