[PATCH v2] powerpc/rtas_flash: fix a potential buffer overflow
From: Yi Zhuang <hidden>
Date: 2021-07-14 12:14:06
Since snprintf() returns the possible output size instead of the actual output size, the available flash_msg length returned by get_validate_flash_msg may exceed the given buffer limit when simple_read_from_buffer calls copy_to_user Reported-by: kernel test robot <redacted> Fixes: a94a14720eaf5 powerpc/rtas_flash: Fix validate_flash buffer overflow issue Signed-off-by: Yi Zhuang <redacted> --- arch/powerpc/kernel/rtas_flash.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/rtas_flash.c b/arch/powerpc/kernel/rtas_flash.c
index a99179d83538..062f0724c2ff 100644
--- a/arch/powerpc/kernel/rtas_flash.c
+++ b/arch/powerpc/kernel/rtas_flash.c@@ -470,9 +470,14 @@ static int get_validate_flash_msg(struct rtas_validate_flash_t *args_buf, if (args_buf->status >= VALIDATE_TMP_UPDATE) { n = sprintf(msg, "%d\n", args_buf->update_results); if ((args_buf->update_results >= VALIDATE_CUR_UNKNOWN) || - (args_buf->update_results == VALIDATE_TMP_UPDATE)) + (args_buf->update_results == VALIDATE_TMP_UPDATE)) { n += snprintf(msg + n, msglen - n, "%s\n", args_buf->buf); + if (n >= msglen) { + n = msglen; + printk(KERN_ERR "FLASH: msg too long.\n"); + } + } } else { n = sprintf(msg, "%d\n", args_buf->status); }
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2.26.0.106.g9fadedd