From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Tue, 24 Feb 2026 20:43:16 +0000 (+0100)
Subject: lib/fileeq: Check arithmetic in ul_fileeq_set_size
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0e6b542b41e9681f70f7b90b2a96bce7beacd978;p=thirdparty%2Futil-linux.git

lib/fileeq: Check arithmetic in ul_fileeq_set_size

Make sure that arithmetics do not overflow data types. Such overflows
could occur with large hardlink options or on 32 bit systems with large
files (due to size_t usage).

If possible, reduce sizes so operations can continue successfully.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
---

diff --git a/include/fileeq.h b/include/fileeq.h
index df5e6d822..90b8d5118 100644
--- a/include/fileeq.h
+++ b/include/fileeq.h
@@ -53,8 +53,8 @@ extern void ul_fileeq_data_init(struct ul_fileeq_data *data);
 extern void ul_fileeq_data_deinit(struct ul_fileeq_data *data);
 extern void ul_fileeq_data_set_file(struct ul_fileeq_data *data,
 				    const char *name);
-extern size_t ul_fileeq_set_size(struct ul_fileeq *eq, uint64_t filesiz,
-                                 size_t readsiz, size_t memsiz);
+extern bool ul_fileeq_set_size(struct ul_fileeq *eq, int64_t st_size,
+                               size_t readsiz, size_t memsiz);
 
 extern int ul_fileeq(struct ul_fileeq *eq,
               struct ul_fileeq_data *a, struct ul_fileeq_data *b);
diff --git a/lib/fileeq.c b/lib/fileeq.c
index d13fc4045..5a56b4753 100644
--- a/lib/fileeq.c
+++ b/lib/fileeq.c
@@ -250,16 +250,23 @@ void ul_fileeq_data_set_file(struct ul_fileeq_data *data, const char *name)
 	data->name = name;
 }
 
-size_t ul_fileeq_set_size(struct ul_fileeq *eq, uint64_t filesiz,
-			 size_t readsiz, size_t memsiz)
+bool ul_fileeq_set_size(struct ul_fileeq *eq, int64_t st_size,
+			size_t readsiz, size_t memsiz)
 {
-	uint64_t nreads, maxdigs;
+	uint64_t filesiz, nreads, maxdigs;
 	size_t digsiz;
 
 	assert(eq);
+	assert(st_size >= 0);
+	assert(readsiz);
+
+	filesiz = (uint64_t) st_size;
 
 	eq->filesiz = filesiz;
 
+	if (filesiz != 0 && readsiz > filesiz)
+		readsiz = filesiz;
+
 	switch (eq->method->id) {
 	case UL_FILEEQ_MEMCMP:
 		/* align file size */
@@ -275,22 +282,28 @@ size_t ul_fileeq_set_size(struct ul_fileeq *eq, uint64_t filesiz,
 		maxdigs = memsiz / digsiz;
 		if (maxdigs == 0)
 			maxdigs = 1;
+		else if (maxdigs > filesiz)
+			maxdigs = filesiz;
 		nreads = filesiz / readsiz;
 		/* enlarge readsize for large files */
-		if (nreads > maxdigs)
-			readsiz = (filesiz + maxdigs - 1) / maxdigs;
+		if (nreads > maxdigs) {
+			uint64_t ceiling = filesiz + maxdigs - 1;
+			if (ceiling / maxdigs > SIZE_MAX)
+				return false;
+			readsiz = ceiling / maxdigs;
+		}
 		break;
 	}
 
 	eq->readsiz = readsiz;
 	eq->blocksmax = (filesiz + readsiz - 1) / readsiz;
 
-	DBG(EQ, ul_debugobj(eq, "set sizes: filesiz=%" PRIu64 ", maxblocks=%" PRIu64 ", readsiz=%zu",
+	DBG(EQ, ul_debugobj(eq, "set sizes: filesiz=%" PRIu64 ", blocksmax=%" PRIu64 ", readsiz=%zu",
 				eq->filesiz, eq->blocksmax, eq->readsiz));
 
 	reset_fileeq_bufs(eq);
 
-	return eq->blocksmax;
+	return true;
 }
 
 static unsigned char *get_buffer(struct ul_fileeq *eq)
@@ -624,8 +637,9 @@ int main(int argc, char *argv[])
 	if (file_c)
 		ul_fileeq_data_set_file(&c, file_c);
 
-	/*                     filesiz,      readsiz,   memsiz */
-	ul_fileeq_set_size(&eq, st_a.st_size, 1024*1024, 4*1024);
+	/*                           st_size,      readsiz,   memsiz */
+	if (!ul_fileeq_set_size(&eq, st_a.st_size, 1024*1024, 4*1024))
+		err(EXIT_FAILURE, "failed to set sizes");
 
 	rc = ul_fileeq(&eq, &a, &b);
 
diff --git a/misc-utils/hardlink.c b/misc-utils/hardlink.c
index 114b5c4c9..2c02e25d4 100644
--- a/misc-utils/hardlink.c
+++ b/misc-utils/hardlink.c
@@ -1097,8 +1097,12 @@ static void visitor(const void *nodep, const VISIT which, const int depth)
 
 		/* per-file cache size */
 		memsiz = opts.cache_size / nnodes;
-		/*                                filesiz,      readsiz,      memsiz */
-		ul_fileeq_set_size(&fileeq, master->st.st_size, opts.io_size, memsiz);
+		/*                               st_size,            readsiz,      memsiz */
+		if (!ul_fileeq_set_size(&fileeq, master->st.st_size, opts.io_size, memsiz)) {
+			jlog(VERBOSE2,
+			     printf(_("Skipped (memory constraints) %s"), master->links->path));
+			continue;
+		}
 
 #ifdef USE_REFLINK
 		if (reflink_mode || reflinks_skip) {