Re: [PATCH] pstore/ram: Fix console ramoops to show the previous boot logs
From: Kees Cook
Date: Thu Jan 17 2019 - 12:11:40 EST
On Wed, Jan 16, 2019 at 10:27 PM Sai Prakash Ranjan
> commit b05c950698fe ("pstore/ram: Simplify ramoops_get_next_prz()
> arguments") changed update assignment in getting next persistent
> ram zone by adding a check for record type. But the check always
> returns true since the record type is assigned 0. And this breaks
> console ramoops by showing current console log instead of previous
> log on warm reset and hard reset (actually hard reset should not
> be showing any logs).
> Fix this by having persistent ram zone type check instead of record
> type check. Tested this on SDM845 MTP and dragonboard 410c.
> Reproducing this issue is simple as below:
> 1. Trigger hard reset and mount pstore. Will see console-ramoops
> record in the mounted location which is the current log.
> 2. Trigger warm reset and mount pstore. Will see the current
> console-ramoops record instead of previous record.
> Fixes: b05c950698fe ("pstore/ram: Simplify ramoops_get_next_prz() arguments")
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
Whoops! Thanks for catching this! I've adjusted the patch slightly (no
need for a local variable), and will send this to Linus.
> I guess commit msg can be improved.
> fs/pstore/ram.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 96f7d32cd184..441a44215456 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -128,7 +128,7 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs, int id,
> struct pstore_record *record)
> struct persistent_ram_zone *prz;
> - bool update = (record->type == PSTORE_TYPE_DMESG);
> + bool update;
> /* Give up if we never existed or have hit the end. */
> if (!przs)
> @@ -138,6 +138,8 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs, int id,
> if (!prz)
> return NULL;
> + update = (prz->type == PSTORE_TYPE_DMESG);
> /* Update old/shadowed buffer. */
> if (update)
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