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[35.233.135.164]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-313286f38c4sm6694653a91.0.2025.06.09.15.12.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Jun 2025 15:12:09 -0700 (PDT) Date: Mon, 9 Jun 2025 22:12:05 +0000 From: Sami Tolvanen To: Petr Pavlu Cc: Luis Chamberlain , Daniel Gomez , linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] module: Fix memory deallocation on error path in move_module() Message-ID: <20250609221205.GA1439779@google.com> References: <20250607161823.409691-1-petr.pavlu@suse.com> <20250607161823.409691-2-petr.pavlu@suse.com> Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, Jun 08, 2025 at 09:25:34AM +0200, Petr Pavlu wrote: > On 6/7/25 6:16 PM, Petr Pavlu wrote: > > The function move_module() uses the variable t to track how many memory > > types it has allocated and consequently how many should be freed if an > > error occurs. > > > > The variable is initially set to 0 and is updated when a call to > > module_memory_alloc() fails. However, move_module() can fail for other > > reasons as well, in which case t remains set to 0 and no memory is freed. > > > > Fix the problem by setting t to MOD_MEM_NUM_TYPES after all memory types > > have been allocated. Additionally, make the deallocation loop more robust > > by not relying on the mod_mem_type_t enum having a signed integer as its > > underlying type. > > > > Fixes: c7ee8aebf6c0 ("module: add stop-grap sanity check on module memcpy()") > > Signed-off-by: Petr Pavlu > > --- > > kernel/module/main.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/module/main.c b/kernel/module/main.c > > index 08b59c37735e..322b38c0a782 100644 > > --- a/kernel/module/main.c > > +++ b/kernel/module/main.c > > [...] > > pr_debug("Final section addresses for %s:\n", mod->name); > > @@ -2693,8 +2694,8 @@ static int move_module(struct module *mod, struct load_info *info) > > return 0; > > out_err: > > module_memory_restore_rox(mod); > > - for (t--; t >= 0; t--) > > - module_memory_free(mod, t); > > + for (; t > 0; t--) > > + module_memory_free(mod, t - 1); > > if (codetag_section_found) > > codetag_free_module_sections(mod); > > > > This can actually be simply: > > while (t--) > module_memory_free(mod, t); Looks correct to me either way. Reviewed-by: Sami Tolvanen Sami