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Date:   Wed, 13 Dec 2023 16:05:06 +0300
From:   Dan Carpenter <dan.carpenter@linaro.org>
To:     oe-kbuild@lists.linux.dev, Charlie Jenkins <charlie@rivosinc.com>
Cc:     lkp@intel.com, oe-kbuild-all@lists.linux.dev,
        linux-kernel@vger.kernel.org, Palmer Dabbelt <palmer@rivosinc.com>
Subject: arch/riscv/kernel/module.c:639 process_accumulated_relocations()
 error: uninitialized symbol 'curr_type'.
Message-ID: <d0897fb3-1af8-430b-aa8b-9aa829bad1d7@suswa.mountain>
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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   cf52eed70e555e864120cfaf280e979e2a035c66
commit: 8fd6c5142395a106b63c8668e9f4a7106b6a0772 riscv: Add remaining module relocations
config: riscv-randconfig-r071-20231211 (https://download.01.org/0day-ci/archive/20231213/202312130859.wnkuzVWY-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 13.2.0
reproduce: (https://download.01.org/0day-ci/archive/20231213/202312130859.wnkuzVWY-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202312130859.wnkuzVWY-lkp@intel.com/

New smatch warnings:
arch/riscv/kernel/module.c:639 process_accumulated_relocations() error: uninitialized symbol 'curr_type'.

Old smatch warnings:
arch/riscv/kernel/module.c:632 process_accumulated_relocations() error: dereferencing freed memory 'rel_entry_iter'
arch/riscv/kernel/module.c:629 process_accumulated_relocations() error: dereferencing freed memory 'rel_head_iter'
arch/riscv/kernel/module.c:628 process_accumulated_relocations() error: dereferencing freed memory 'bucket_iter'

vim +/curr_type +639 arch/riscv/kernel/module.c

8fd6c5142395a1 Charlie Jenkins 2023-11-01  602  void process_accumulated_relocations(struct module *me)
8fd6c5142395a1 Charlie Jenkins 2023-11-01  603  {
8fd6c5142395a1 Charlie Jenkins 2023-11-01  604  	/*
8fd6c5142395a1 Charlie Jenkins 2023-11-01  605  	 * Only ADD/SUB/SET/ULEB128 should end up here.
8fd6c5142395a1 Charlie Jenkins 2023-11-01  606  	 *
8fd6c5142395a1 Charlie Jenkins 2023-11-01  607  	 * Each bucket may have more than one relocation location. All
8fd6c5142395a1 Charlie Jenkins 2023-11-01  608  	 * relocations for a location are stored in a list in a bucket.
8fd6c5142395a1 Charlie Jenkins 2023-11-01  609  	 *
8fd6c5142395a1 Charlie Jenkins 2023-11-01  610  	 * Relocations are applied to a temp variable before being stored to the
8fd6c5142395a1 Charlie Jenkins 2023-11-01  611  	 * provided location to check for overflow. This also allows ULEB128 to
8fd6c5142395a1 Charlie Jenkins 2023-11-01  612  	 * properly decide how many entries are needed before storing to
8fd6c5142395a1 Charlie Jenkins 2023-11-01  613  	 * location. The final value is stored into location using the handler
8fd6c5142395a1 Charlie Jenkins 2023-11-01  614  	 * for the last relocation to an address.
8fd6c5142395a1 Charlie Jenkins 2023-11-01  615  	 *
8fd6c5142395a1 Charlie Jenkins 2023-11-01  616  	 * Three layers of indexing:
8fd6c5142395a1 Charlie Jenkins 2023-11-01  617  	 *	- Each of the buckets in use
8fd6c5142395a1 Charlie Jenkins 2023-11-01  618  	 *	- Groups of relocations in each bucket by location address
8fd6c5142395a1 Charlie Jenkins 2023-11-01  619  	 *	- Each relocation entry for a location address
8fd6c5142395a1 Charlie Jenkins 2023-11-01  620  	 */
8fd6c5142395a1 Charlie Jenkins 2023-11-01  621  	struct used_bucket *bucket_iter;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  622  	struct relocation_head *rel_head_iter;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  623  	struct relocation_entry *rel_entry_iter;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  624  	int curr_type;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  625  	void *location;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  626  	long buffer;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  627  
8fd6c5142395a1 Charlie Jenkins 2023-11-01  628  	list_for_each_entry(bucket_iter, &used_buckets_list, head) {
8fd6c5142395a1 Charlie Jenkins 2023-11-01  629  		hlist_for_each_entry(rel_head_iter, bucket_iter->bucket, node) {
8fd6c5142395a1 Charlie Jenkins 2023-11-01  630  			buffer = 0;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  631  			location = rel_head_iter->location;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  632  			list_for_each_entry(rel_entry_iter,
8fd6c5142395a1 Charlie Jenkins 2023-11-01  633  					    rel_head_iter->rel_entry, head) {
8fd6c5142395a1 Charlie Jenkins 2023-11-01  634  				curr_type = rel_entry_iter->type;
8fd6c5142395a1 Charlie Jenkins 2023-11-01  635  				reloc_handlers[curr_type].reloc_handler(
8fd6c5142395a1 Charlie Jenkins 2023-11-01  636  					me, &buffer, rel_entry_iter->value);
8fd6c5142395a1 Charlie Jenkins 2023-11-01  637  				kfree(rel_entry_iter);

This kfree() will lead to a NULL dereference on the next iteration
through the loop.  You need to use list_for_each_entry_safe().

8fd6c5142395a1 Charlie Jenkins 2023-11-01  638  			}
8fd6c5142395a1 Charlie Jenkins 2023-11-01 @639  			reloc_handlers[curr_type].accumulate_handler(
                                                                                       ^^^^^^^^^
Can the list be empty?  Uninitialized in that case.

8fd6c5142395a1 Charlie Jenkins 2023-11-01  640  				me, location, buffer);
8fd6c5142395a1 Charlie Jenkins 2023-11-01  641  			kfree(rel_head_iter);
8fd6c5142395a1 Charlie Jenkins 2023-11-01  642  		}
8fd6c5142395a1 Charlie Jenkins 2023-11-01  643  		kfree(bucket_iter);
8fd6c5142395a1 Charlie Jenkins 2023-11-01  644  	}
8fd6c5142395a1 Charlie Jenkins 2023-11-01  645  
8fd6c5142395a1 Charlie Jenkins 2023-11-01  646  	kfree(relocation_hashtable);
8fd6c5142395a1 Charlie Jenkins 2023-11-01  647  }

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