* [PATCH] kdb: Reject zero BYTESPERWORD before calculating the repeat count
@ 2026-11-13 11:11 Alex Kazinsky
0 siblings, 0 replies; only message in thread
From: Alex Kazinsky @ 2026-11-13 11:11 UTC (permalink / raw)
To: Daniel Thompson
Cc: Alex Kazinsky, Douglas Anderson, Naveen Kumar Chaudhary,
Greg Kroah-Hartman, Tim Bird, Martin Hicks, kgdb-bugreport,
linux-kernel, lvc-project
Setting BYTESPERWORD to zero in the kdb environment causes kdb_md()
to divide by zero when calculating the initial repeat count. The
existing width validation happens after this division.
Reject a zero width with KDB_BADWIDTH before calculating the repeat
count.
Found by Linux Verification Center (linuxtesting.org) with SVACE static
analysis tool.
Fixes: 5d5314d6795f ("kdb: core for kgdb back end (1 of 2)")
Signed-off-by: Alex Kazinsky <a.kazinsky@ideco.ru>
---
kernel/debug/kdb/kdb_main.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 40c332d2179d..c3cbeb25f6fb 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1527,6 +1527,9 @@ static int kdb_md(int argc, const char **argv)
kdbgetintenv("RADIX", &radix);
kdbgetintenv("BYTESPERWORD", &bytesperword);
+ if (!bytesperword)
+ return KDB_BADWIDTH;
+
/* Assume 'md <addr>' and start with environment values */
repeat = mdcount * 16 / bytesperword;
--
2.56.0
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