[PATCH] lib/mpi: Fix buffer overrun when SG is too long
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: 2022-12-20 07:25:47
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Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
On Mon, Dec 19, 2022 at 09:49:29AM +0100, Roberto Sassu wrote:
do you have any news on this bug?
Thanks for the reminder. Could you please try this patch?
---8<---
The helper mpi_read_raw_from_sgl ignores the second parameter
nbytes when reading the SG list and may overrun its own buffer
because it only allocates enough memory according to nbytes.
Fixes: 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers")
Reported-by: Roberto Sassu <redacted>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 39c4c6731094..6bffc68c1a5a 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c@@ -494,17 +494,15 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes) val->sign = 0; val->nlimbs = nlimbs; - if (nbytes == 0) - return val; - j = nlimbs - 1; a = 0; z = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; z %= BYTES_PER_MPI_LIMB; - while (sg_miter_next(&miter)) { + while (nbytes && sg_miter_next(&miter)) { buff = miter.addr; - len = miter.length; + len = min_t(unsigned, miter.length, nbytes); + nbytes -= len; for (x = 0; x < len; x++) { a <<= 8;
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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