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kconfig: fix potential NULL pointer dereference in conf_askvalue

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[ Upstream commit b9d21c32dc ]

In conf_askvalue(), the 'def' argument (retrieved via sym_get_string_value)
can be NULL. While current call sites ensure that 'def' is valid,
calling printf("%s\n", def) is technically undefined behavior and could
lead to a segmentation fault on certain libc implementations if the
function were called with a NULL pointer in the future.

Improve the robustness of conf_askvalue() by providing an empty string
as a fallback.

Additionally, remove the redundant re-initialization of the 'line'
buffer inside the !sym_is_changeable(sym) block, as it is already
properly initialized at the function entry.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Xingjing Deng <micro6947@gmail.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260306021709.27068-1-micro6947@gmail.com
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Xingjing Deng
2026-07-24 16:15:45 +02:00
committed by Greg Kroah-Hartman
parent ad445de673
commit fbeea02c35
1 changed files with 2 additions and 4 deletions
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scripts/kconfig/conf.c
+2 -4
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@@ -297,9 +297,7 @@ static int conf_askvalue(struct symbol *sym, const char *def)
line[1] = 0;
if (!sym_is_changeable(sym)) {
printf("%s\n", def);
line[0] = '\n';
line[1] = 0;
printf("%s\n", def ?: "");
return 0;
}
@@ -307,7 +305,7 @@ static int conf_askvalue(struct symbol *sym, const char *def)
case oldconfig:
case syncconfig:
if (sym_has_value(sym)) {
printf("%s\n", def);
printf("%s\n", def ?: "");
return 0;
}
/* fall through */