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udebug: fix crash in udebug_entry_vprintf with longer strings

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The passed va_list ap cannot be used more than once. In order to deal with
vsprintf retry, it needs to be copied first. Fixes a procd crash observed
on several platforms.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2024-01-26 21:00:14 +01:00
parent 6339204c21
commit c1be505732
1 changed files with 4 additions and 1 deletions
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5
udebug.c
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@ -610,6 +610,7 @@ int udebug_entry_vprintf(struct udebug_buf *buf, const char *fmt, va_list ap)
struct udebug_ptr *ptr;
uint32_t ofs;
uint32_t len;
va_list ap2;
char *str;
if (!hdr)
@ -621,7 +622,9 @@ int udebug_entry_vprintf(struct udebug_buf *buf, const char *fmt, va_list ap)
return -1;
str = udebug_buf_alloc(buf, ofs, UDEBUG_MIN_ALLOC_LEN);
len = vsnprintf(str, UDEBUG_MIN_ALLOC_LEN, fmt, ap);
va_copy(ap2, ap);
len = vsnprintf(str, UDEBUG_MIN_ALLOC_LEN, fmt, ap2);
va_end(ap2);
if (len <= UDEBUG_MIN_ALLOC_LEN)
goto out;