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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2023-03-14 19:17:31 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2023-03-14 19:17:31 -0400 |
| commit | b081fe4199b69dc561f7d31c6a82b3ad996f657f (patch) | |
| tree | 75cdcdaf8a38e35b09677d74fd4ecb5a11848292 /src/backend/utils/adt/formatting.c | |
| parent | a563c24c9574b74f4883c004c89275bba03c3c26 (diff) | |
| download | postgresql-b081fe4199b69dc561f7d31c6a82b3ad996f657f.tar.gz postgresql-b081fe4199b69dc561f7d31c6a82b3ad996f657f.zip | |
Fix corner case bug in numeric to_char() some more.
The band-aid applied in commit f0bedf3e4 turns out to still need
some work: it made sure we didn't set Np->last_relevant too small
(to the left of the decimal point), but it didn't prevent setting
it too large (off the end of the partially-converted string).
This could result in fetching data beyond the end of the allocated
space, which with very bad luck could cause a SIGSEGV, though
I don't see any hazard of interesting memory disclosure.
Per bug #17839 from Thiago Nunes. The bug's pretty ancient,
so back-patch to all supported versions.
Discussion: https://postgr.es/m/17839-aada50db24d7b0da@postgresql.org
Diffstat (limited to 'src/backend/utils/adt/formatting.c')
| -rw-r--r-- | src/backend/utils/adt/formatting.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c index f3f4db5ef60..e6246dc44bd 100644 --- a/src/backend/utils/adt/formatting.c +++ b/src/backend/utils/adt/formatting.c @@ -5695,13 +5695,20 @@ NUM_processor(FormatNode *node, NUMDesc *Num, char *inout, /* * If any '0' specifiers are present, make sure we don't strip - * those digits. + * those digits. But don't advance last_relevant beyond the last + * character of the Np->number string, which is a hazard if the + * number got shortened due to precision limitations. */ if (Np->last_relevant && Np->Num->zero_end > Np->out_pre_spaces) { + int last_zero_pos; char *last_zero; - last_zero = Np->number + (Np->Num->zero_end - Np->out_pre_spaces); + /* note that Np->number cannot be zero-length here */ + last_zero_pos = strlen(Np->number) - 1; + last_zero_pos = Min(last_zero_pos, + Np->Num->zero_end - Np->out_pre_spaces); + last_zero = Np->number + last_zero_pos; if (Np->last_relevant < last_zero) Np->last_relevant = last_zero; } |