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PCI/P2PDMA: Safely terminate ACS redirect lists

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seq_buf marks an overflow by setting len to size + 1. The ACS diagnostic
path unconditionally writes a terminator to buffer[len - 1], so a path with
enough ACS ports to fill the 128-byte buffer writes one byte beyond the
buffer when verbose diagnostics are requested.

Use seq_buf_str() to terminate truncated output safely and remove the final
semicolon only when the buffer did not overflow.

Fixes: 52916982af ("PCI/P2PDMA: Support peer-to-peer memory")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Tushar Dave <tdave@nvidia.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://patch.msgid.link/20260830-batch-p2p-fixes-v1-4-5044e8dfbe2e@nvidia.com
This commit is contained in:
Leon Romanovsky 2026-08-30 14:16:22 +03:00 committed by Bjorn Helgaas
parent ae57c51f0f
commit fa291d6429
1 changed files with 4 additions and 2 deletions
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6
drivers/pci/p2pdma.c
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@ -784,11 +784,13 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
}
if (verbose) {
acs_list.buffer[acs_list.len-1] = 0; /* drop final semicolon */
/* Drop the final semicolon; the list is not empty here */
if (!seq_buf_has_overflowed(&acs_list))
acs_list.buffer[acs_list.len - 1] = '\0';
pci_warn(client, "ACS redirect is set between the client and provider (%s)\n",
pci_name(provider));
pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
acs_list.buffer);
seq_buf_str(&acs_list));
}
acs_redirects = true;