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From: Benjamin Poirier <bpoirier@nvidia.com>
To: kexec@lists.infradead.org
Subject: [PATCH v2 makedumpfile 1/3] Fix off by one error when checking cache_size
Date: Thu, 8 Jul 2021 16:06:09 +0900	[thread overview]
Message-ID: <20210708070611.291260-2-bpoirier@nvidia.com> (raw)
In-Reply-To: <20210708070611.291260-1-bpoirier@nvidia.com>

Given the test in write_cache():
	if (cd->buf_size < cd->cache_size)
		return TRUE;
a write is done if buf_size == cache_size.
The test at the beginning of write_kdump_page() intends to detect cases
when write_cache() will do a write, however it was missing this boundary
condition. This would lead write_kdump_page() to ignore errors from
write_cache().

Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
---
 makedumpfile.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index fcb571f..aa05be7 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -7993,8 +7993,8 @@ write_kdump_page(struct cache_data *cd_header, struct cache_data *cd_page,
 	 * write the buffer cd_header into dumpfile and then write the cd_page.
 	 * With that, when enospc occurs, we can save more useful information.
 	 */
-	if (cd_header->buf_size + sizeof(*pd) > cd_header->cache_size
-		|| cd_page->buf_size + pd->size > cd_page->cache_size){
+	if (cd_header->buf_size + sizeof(*pd) >= cd_header->cache_size ||
+	    cd_page->buf_size + pd->size >= cd_page->cache_size) {
 		if( !write_cd_buf(cd_header) ) {
 			memset(cd_header->buf, 0, cd_header->cache_size);
 			write_cd_buf(cd_header);
-- 
2.32.0


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  reply	other threads:[~2021-07-08  7:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-08  7:06 [PATCH v2 makedumpfile 0/3] Add option to limit file size Benjamin Poirier
2021-07-08  7:06 ` Benjamin Poirier [this message]
2021-07-08  7:06 ` [PATCH v2 makedumpfile 2/3] Dump dmesg using write_and_check_space() Benjamin Poirier
2021-07-08  7:06 ` [PATCH v2 makedumpfile 3/3] Add -L option to limit output file size Benjamin Poirier
2021-07-30  2:13 ` [PATCH v2 makedumpfile 0/3] Add option to limit " HAGIO KAZUHITO(萩尾　一仁)
2021-07-30  3:51   ` Benjamin Poirier

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