Re: [PATCH 3/3] parse: replace atoi() with strtoul_ui() and strtol_i()

From: Phillip Wood <phillip.wood123@gmail.com>
Date: Oct 14, 2024, 09:49 UTC
Message-ID: <6875cb49-becc-4562-ace8-9f07848a345c@gmail.com>
In-Reply-To: <c93bc2d81ffb33a2a61dda2878fa3b9987545e0b.1728774574.git.gitgitgadget@gmail.com>

Hi Usman

On 13/10/2024 00:09, Usman Akinyemi via GitGitGadget wrote:

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> From: Usman Akinyemi <usmanakinyemi202@gmail.com>
> 
> Replace unsafe uses of atoi() with strtoul_ui() for unsigned integers
> and strtol_i() for signed integers across multiple files. This change
> improves error handling and prevents potential integer overflow issues.

This paragraph is good as it explains why you are making this change

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> The following files were updated:
> - daemon.c: Update parsing of --timeout, --init-timeout, and
>    --max-connections
> - imap-send.c: Improve parsing of UIDVALIDITY, UIDNEXT, APPENDUID, and
>    tags
> - merge-ll.c: Enhance parsing of marker size in ll_merge and
>    ll_merge_marker_size

This information is not really needed in the commit message as it is shown in the diff.

> This change allows for better error detection when parsing integer
> values from command-line arguments and IMAP responses, making the code
> more robust and secure.

Great

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> This is a #leftoverbit discussed here:
>   https://public-inbox.org/git/CAC4O8c-nuOTS=a0sVp1603KaM2bZjs+yNZzdAaa5CGTNGFE7hQ@mail.gmail.com/
> 
> Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
> 
> Cc: gitster@pobox.com
> Cc: Patrick Steinhardt <ps@pks.im>
> Cc: phillip.wood123@gmail.com
> Cc: Christian Couder <christian.couder@gmail.com>
> Cc: Eric Sunshine <sunshine@sunshineco.com>
> Cc: Taylor Blau <me@ttaylorr.com>

We do not tend to use Cc: footers on this list. Also note that as there 
is a blank line between the Signed-off-by: line and this paragraph the 
Signed-off-by: will be ignored by git-interpret-trailers.

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> ---
>   daemon.c    | 14 +++++++++-----
>   imap-send.c | 13 ++++++++-----
>   merge-ll.c  |  6 ++----
>   3 files changed, 19 insertions(+), 14 deletions(-)
> 
> diff --git a/daemon.c b/daemon.c
> index cb946e3c95f..3fdb6e83c40 100644
> --- a/daemon.c
> +++ b/daemon.c
> @@ -1308,17 +1308,21 @@ int cmd_main(int argc, const char **argv)
>   			continue;
>   		}
>   		if (skip_prefix(arg, "--timeout=", &v)) {
> -			timeout = atoi(v);
> +			if (strtoul_ui(v, 10, &timeout) < 0) {

For functions that return 0 or -1 to indicate success or error respectively we use "if (func(args))" to check for errors.

> +				die("'%s': not a valid integer for --timeout", v);

"-1" is a valid integer but it is not a valid timeout, maybe we could say something like "invalid timeout '%s', expecting a non-negative integer".

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> +			}
>   			continue;
>   		}
>   		if (skip_prefix(arg, "--init-timeout=", &v)) {
> -			init_timeout = atoi(v);
> +			if (strtoul_ui(v, 10, &init_timeout) < 0) {
> +				die("'%s': not a valid integer for --init-timeout", v);

The comments for --timeout apply here as well

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> +			}
>   			continue;
>   		}
>   		if (skip_prefix(arg, "--max-connections=", &v)) {
> -			max_connections = atoi(v);
> -			if (max_connections < 0)
> -				max_connections = 0;	        /* unlimited */
> +			if (strtol_i(v, 10, &max_connections) != 0 || max_connections < 0) {

This is a faithful translation but if the aim of this series is to detect errors then I think we want to do something like

	if (strtol_i(v, 10, &max_connections))
		die(...)
	if (max_connections < 0)
		max_connections = 0; /* unlimited */

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> +				max_connections = 0;  /* unlimited */
> +			}
>   			continue;
>   		}
>   		if (!strcmp(arg, "--strict-paths")) {
> diff --git a/imap-send.c b/imap-send.c
> index ec68a066877..33b74dfded7 100644
> --- a/imap-send.c
> +++ b/imap-send.c
> @@ -668,12 +668,12 @@ static int parse_response_code(struct imap_store *ctx, struct imap_cmd_cb *cb,
>   		return RESP_BAD;
>   	}
>   	if (!strcmp("UIDVALIDITY", arg)) {
> -		if (!(arg = next_arg(&s)) || !(ctx->uidvalidity = atoi(arg))) {
> +		if (!(arg = next_arg(&s)) || strtol_i(arg, 10, &ctx->uidvalidity) != 0) {

The original is checking for a zero return from atoi() which indicates an error or that the parsed value was zero. To do that with strtol_i() we need to do

	|| (strtol_i(arg, 10, &ctx->uidvalidity) || !ctx->uidvalidity)

The IMAP RFC[1] specifies that UIDVALIDITY should be a non-zero, non-negative 32bit integer but I'm not sure we want to start change it's type and using strtoul_ui here.

[1] https://www.rfc-editor.org/rfc/rfc3501#section-2.3.1.1

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>   			fprintf(stderr, "IMAP error: malformed UIDVALIDITY status\n");
>   			return RESP_BAD;
>   		}
>   	} else if (!strcmp("UIDNEXT", arg)) {
> -		if (!(arg = next_arg(&s)) || !(imap->uidnext = atoi(arg))) {
> +		if (!(arg = next_arg(&s)) || strtol_i(arg, 10, &imap->uidnext) != 0) {

The comments above apply here

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>   			fprintf(stderr, "IMAP error: malformed NEXTUID status\n");
>   			return RESP_BAD;
>   		}
> @@ -686,8 +686,8 @@ static int parse_response_code(struct imap_store *ctx, struct imap_cmd_cb *cb,
>   		for (; isspace((unsigned char)*p); p++);
>   		fprintf(stderr, "*** IMAP ALERT *** %s\n", p);
>   	} else if (cb && cb->ctx && !strcmp("APPENDUID", arg)) {
> -		if (!(arg = next_arg(&s)) || !(ctx->uidvalidity = atoi(arg)) ||
> -		    !(arg = next_arg(&s)) || !(*(int *)cb->ctx = atoi(arg))) {
> +		if (!(arg = next_arg(&s)) || (strtol_i(arg, 10, &ctx->uidvalidity) != 0) ||
> +			!(arg = next_arg(&s)) || (strtol_i(arg, 10, (int *)cb->ctx) != 0)) {

And here

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>   			fprintf(stderr, "IMAP error: malformed APPENDUID status\n");
>   			return RESP_BAD;
>   		}
> @@ -773,7 +773,10 @@ static int get_cmd_result(struct imap_store *ctx, struct imap_cmd *tcmd)
>   			if (!tcmd)
>   				return DRV_OK;
>   		} else {
> -			tag = atoi(arg);
> +			if (strtol_i(arg, 10, &tag) != 0) {

To check for an error just use (strtol_i(arg, 10, &tag))

> +				fprintf(stderr, "IMAP error: malformed tag %s\n", arg);
> +				return RESP_BAD;

This matches the error below so I assume it's good.

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> +			}
>   			for (pcmdp = &imap->in_progress; (cmdp = *pcmdp); pcmdp = &cmdp->next)
>   				if (cmdp->tag == tag)
>   					goto gottag;
> diff --git a/merge-ll.c b/merge-ll.c
> index 8e63071922b..2bfee0f2c6b 100644
> --- a/merge-ll.c
> +++ b/merge-ll.c
> @@ -427,8 +427,7 @@ enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
>   	git_check_attr(istate, path, check);
>   	ll_driver_name = check->items[0].value;
>   	if (check->items[1].value) {
> -		marker_size = atoi(check->items[1].value);
> -		if (marker_size <= 0)
> +		if (strtol_i(check->items[1].value, 10, &marker_size) != 0 || marker_size <= 0)

Here I think we want to return an error if we cannot parse the marker size and then set the default if the marker size is <= 0 like we do for the max_connections code in daemon.c above.

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>   			marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
>   	}
>   	driver = find_ll_merge_driver(ll_driver_name);
> @@ -454,8 +453,7 @@ int ll_merge_marker_size(struct index_state *istate, const char *path)
>   		check = attr_check_initl("conflict-marker-size", NULL);
>   	git_check_attr(istate, path, check);
>   	if (check->items[0].value) {
> -		marker_size = atoi(check->items[0].value);
> -		if (marker_size <= 0)
> +		if (strtol_i(check->items[0].value, 10, &marker_size) != 0 || marker_size <= 0)

And the same here

Thanks for working on this, it will be a useful improvement to our integer parsing. I think you've got the basic idea, it just needs a bit of polish

Phillip